No.

47 Shipbuilding and Repair Quality Standard

(1996)
(Rev. 1, 1999)
(Rev.2, Dec. 2004)
(Rev.3, Nov. 2006)

Part A Shipbuilding and Repair Quality Standard for New Construction

Part B Repair Quality Standard for Existing Ships

PART A - SHIPBUILDING AND REPAIR QUALITY STANDARDS FOR NEW CONSTRUCTION

1. Scope
2. General requirements for new construction
3. Qualification of personnel and procedures
3.1 Qualification of welders
3.2 Qualification of welding procedures
3.3 Qualification of NDE operators
4. Materials
4.1 Materials for structural members
4.2 Under thickness tolerances
4.3 Surface conditions
5. Cutting
5.1 Gas cutting
6. Fabrication and fairness
6.1 Flanged longitudinals and flanged brackets
6.2 Built-up sections
6.3 Corrugated bulkheads
6.4 Pillars, brackets and stiffeners
6.5 Maximum heating temperature on surface for line heating
6.6 Block assembly
6.7 Special sub-assembly
6.8 Shape
6.9 Fairness of plating between frames
6.10 Fairness of plating with frames
6.11 Preheating for welding hull steels at low temperature
7. Alignment
8. Welding
8.1 Typical butt weld plate edge preparation (manual welding)
8.2 Typical fillet weld plate edge preparation (manual welding)
8.3 Typical butt and fillet weld profile (manual welding)
8.4 Lap, plug and slot welding
8.5 Distance between welds
8.6 Automatic welding
9. Repair
9.1 Typical misalignment repair
9.2 Typical butt weld plate edge preparation repair (manual welding)
9.3 Typical fillet weld plate edge preparation repair (manual welding)
9.4 Typical fillet and butt weld profile repair (manual welding)
9.5 Distance between welds repair
9.6 Erroneous hole repair
9.7 Repair by insert plate
9.8 Weld surface repair

REFERENCES

1. IACS “Bulk Carriers - Guidelines for Surveys, Assessment and Repair of Hull Structure”
2. TSCF “Guidelines for the inspection and maintenance of double hull tanker structures”

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3. TSCF “Guidance manual for the inspection and condition assessment of tanker structures”
4. IACS UR W7 “Hull and machinery steel forgings”
5. IACS UR W8 “Hull and machinery steel castings”
6. IACS UR W11 “Normal and higher strength hull structural steel”
7. IACS UR W13 “Allowable under thickness tolerances of steel plates and wide flats”
8. IACS UR W14 “Steel plates and wide flats with improved through thickness properties”
9. IACS UR W17 “Approval of consumables for welding normal and higher strength hull structural steels”
10. IACS UR Z10.1 “Hull surveys of oil tankers” and Z10.2 “Hull surveys of bulk carriers” Annex I
11. IACS Recommendation No. 12 “Guidelines for surface finish of hot rolled plates and wide flats “
13. IACS Recommendation No. 20 “ Guide for inspection of ship hull welds”

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1. Scope

1.1 This standard provides guidance on shipbuilding quality standards for the hull structure during new
construction and the repair standard where the quality standard is not met.

Whereas the standard generally applies to

- conventional ship types,
- parts of hull covered by the rules of the Classification Society,
- hull structures constructed from normal and higher strength hull structural steel,
the applicability of the standard is in each case to be agreed upon by the Classification Society.

The standard does generally not apply to the new construction of

- special types of ships as e.g. gas tankers
- structures fabricated from stainless steel or other, special types or grades of steel

1.2 The standard covers typical construction methods and gives guidance on quality standards for the
most important aspects of such construction. Unless explicitly stated elsewhere in the standard, the level
of workmanship reflected herein will in principle be acceptable for primary and secondary structure of
conventional designs. A more stringent standard may however be required for critical and highly
stressed areas of the hull, and this is to be agreed with the Classification Society in each case. In
assessing the criticality of hull structure and structural components, reference is made to ref. 1, 2 and 3.

1.3 Details relevant to structures or fabrication procedures not covered by this standard are to be
approved by the Classification Society on the basis of procedure qualifications and/or recognized
national standards.

1.4 It is intended that these standards provide guidance where established shipbuilding or national
standards approved by the Classification Society do not exist.

1.5 For use of this standard, fabrication fit-ups, deflections and similar quality attributes are intended to
be uniformly distributed about the nominal values. The shipyard is to take corrective action to improve
work processes that produce measurements where a skewed distribution is evident. Relying upon
remedial steps that truncate a skewed distribution of the quality attribute is unacceptable.

1.6 In this standard, both a "Standard" range and a "Limit" range are listed. The "Standard" range
represents the target range expected to be met in regular work under normal circumstances. The "Limit"
range represents the maximum allowable deviation from the "Standard" range. Work beyond the
"Standard" range but within the "Limit" range is acceptable.

2. General requirements for new construction

2.1 In general, the work is to be carried out in accordance with the Classification Society rules and under
the supervision of the Surveyor to the Classification Society

2.2 Provisions are to be made for proper accessibility, staging, lighting and ventilation. Welding
operations are to be carried out under shelter from rain, snow and wind.

2.3 Welding of hull structures is to be carried out by qualified welders, according to approved and
qualified welding procedures and with welding consumables approved by the Classification Society, see
Section 3. Welding operations are to be carried out under proper supervision by the shipbuilder.

3. Qualification of personnel and procedures

3.1 Qualification of welders

3.1.1 Welders are to be qualified in accordance with the procedures of the Classification Society or to a

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 recognized national or international standard, e.g. EN 287, ISO 9606, ASME Section IX, ANSI/AWS
D1.1. Recognition of other standards is subject to submission to the Classification Society for evaluation.
Subcontractors are to keep records of welders qualification and, when required, furnish valid approval
test certificates.

3.1.2 Welding operators using fully mechanized or fully automatic processes need generally not pass
approval testing provided that the production welds made by the operators are of the required quality.
However, operators are to receive adequate training in setting or programming and operating the
equipment Records of training and production test results shall be maintained on individual operator’s
files and records, and be made available to the Classification Society for inspection when requested.

3.2 Qualification of welding procedures

Welding procedures are to be qualified in accordance with the procedures of the Classification
Society or a recognized national or international standard, e.g. EN288, ISO 9956, ASME Section IX,
ANSI/AWS D1.1. Recognition of other standards is subject to submission to the Classification Society
for evaluation. The welding procedure should be supported by a welding procedure qualification
record. The specification is to include the welding process, types of electrodes, weld shape, edge
preparation, welding techniques and positions.

3.3 Qualification of NDE operators

3.3.1 Personnel performing non-destructive examination for the purpose of assessing quality of welds in
connection with new construction covered by this standard, are to be qualified in accordance with
Classification Society rules or to a recognized international or national qualification scheme. Records of
operators and their current certificates are to be kept and made available to the Surveyor for inspection.

4. Materials

4.1 Materials for Structural Members

All materials, including weld consumables, to be used for the structural members are to be approved
by the Classification Society as per the approved construction drawings and meet the respective IACS
Unified Requirements. Additional recommendations are contained in the following paragraphs.

All materials used should be manufactured at a works approved by the Classification Society for the
type and grade supplied.

4.2 Surface Conditions

4.2.1 Definitions

Minor Imperfections: pittings, rolled-in scale, indentations, roll marks, scratches and grooves
Defects: Cracks, shells, sand patches, sharp edged seams and minor imperfections
not exceeding the limits of table 1 in case that the sum of the influenced
area exceeds 5% of the total surface in question
Depth of Imperfections or defects: the depth is to be measured from the surface of the product

4.2.2 Unrepaired Conditions

Minor imperfections, in accordance with the limits described in Table 1, are permissible and may be left
unrepaired.

4.2.3 Repairs of Defects

Defects are to be repaired by grinding or welding irrespective of their size and number. Repair by
grinding may be carried out over the entire surface up to a depth equal to –0.3mm.

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4.2.4 Repairs by Grinding

The nominal thickness is not to be reduced by more than 7% or 3mm, whichever is the lesser. Each
single ground area is not to exceed 0.25m2 .

The defects are to be completely removed by grinding. Complete elimination of the defects is to be
verified by a magnetic particle or dye penetrant test procedure. The ground areas must have smooth
transitions to the surrounding surface.

4.2.5 Repairs by welding

Local defects, which cannot be repaired by grinding, may be repaired by chipping and/or grinding
followed by welding in accordance with the qualified procedures approved by the Classification Society
concerned.

Any single welded area is not to exceed 0.125m2. The weld preparation should not reduce the
thickness of the product below 80% of the nominal thickness. Welding is to be completed with one layer
of weld bead in excess, which is subsequently to be ground smooth, level with the plate surface. The
soundness of the repair is to be verified by ultrasonic, magnetic particle or dye penetrant methods.

Imperfection surface area Ratio(%) 15～20% 5～15% 0～5%

t < 20mm 0.2mm 0.4mm 0.5mm
20mm ≤ t < 50mm 0.2mm 0.6mm 0.7mm
50mm ≤ t 0.2mm 0.7mm 0.9mm

Table 1 Limits for minor imperfections left unrepaired

4.2.6 Further Defects

4.2.6.1 Lamination

Investigation to be carried out at the steelmill into the cause and extent of the laminations. Severe
lamination is to be repaired by local insert plates. The minimum breadth or length of the plate to be
replaced is to be:

• 1600mm for shell and strength deck plating in way of cruciform or T-joints,
• 800mm for shell, strength deck plating and other primary members,
• 300mm for other structural members.

Local limited lamination may be repaired by chipping and/or grinding followed by welding in
accordance with sketch (a). In case where the local limited lamination is near the plate surface, the
repair may be carried out as shown in sketch (b). For limitations see paragraph 4.2.5.

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 (a) (b)

4.2.6.2 Weld Spatters

Loose weld spatters are to be removed completely by grinding or other measures to clean metal (see
Table 9.13) on:
• shell plating
• deck plating on exposed decks
• in tanks for chemical cargoes
• in tanks for fresh water and for drinking water
• in tanks for lubricating oil, hydraulic oil, including service tanks

5. Cutting

5.1 Gas Cutting

The roughness of the cut edges R is to meet the following requirements:

Free Edges:
Standard Limit
Strength Members 150µm 300µm
Others 500µm 1000µm

Welding Edges:
Standard Limit
Strength Members 400µm 800µm
Others 800µm 1500µm

6. Fabrication and fairness

6.1 Flanged longitudinals and flanged brackets (see Table 6.1)

6.2 Built-up sections (see Table 6.2)
6.3 Corrugated bulkheads (see Table 6.3)
6.4 Pillars, brackets and stiffeners (see Table 6.4)
6.5 Maximum heating temperature on surface for line heating (see Table 6.5)
6.6 Block assembly (see Table 6.6)
6.7 Special sub-assembly (see Table 6.7)
6.8 Shape (see Table 6.8 and 6.9)
6.9 Fairness of plating between frames (see Table 6.10)
6.10 Fairness of plating with frames (see Table 6.11)
6.11 Preheating for welding hull steels at low temperature (See Table 6.12)

7. Alignment

The quality standards for alignment of hull structural components during new construction are shown in
Tables 7.1, 7.2 and 7.3. The Classification Society may require a closer construction tolerance in areas
requiring special attention, as follows:

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 • Regions exposed to high stress concentrations
• Fatigue prone areas
• Detail design block erection joints
• Higher tensile steel regions

8. Welding Details

8.1 Typical butt weld plate edge preparation (manual welding) - see Table 8.1 and 8.2
8.2 Typical fillet weld plate edge preparation (manual welding) - see Table 8.3 and 8.4
8.3 Typical butt and fillet weld profile (manual welding) - see Table 8.5
8.4 Distance between welds - see Table 8.6
8.5 Automatic welding - see Table 8.7

9. Repair

9.1 Typical misalignment repair - see Tables 9.1 to 9.3

9.2 Typical butt weld plate edge preparation repair (manual welding) - see Table 9.4 and 9.5
9.3 Typical fillet weld plate edge preparation repair (manual welding) - see Tables 9.6 to 9.8
9.4 Typical fillet and butt weld profile repair (manual welding) - see Table 9.9
9.5 Distance between welds repair - see Table 9.10
9.6 Erroneous hole repair - see Table 9.11
9.7 Repair by insert plate - see Table 9.12
9.8 Weld surface repair - see Table 9.13

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TABLE 6.1 – Flanged Longitudinals and Flanged Brackets

Detail Standard Limit Remarks

Breadth of flange

+ 3 mm + 5 mm

compared to correct size

Angle between flange and

web

+ 3 mm + 5 mm per 100 mm of a

compared to template

Straightness in plane of
flange and web

+ 10 mm + 25 mm per 10 m

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TABLE 6.2 – Built Up Sections

Detail Standard Limit Remarks

Frames and longitudinal

+ 1.5mm + 3mm per 100 mm of a

Distortion of face plate

d ≤ 3 + a/100 mm d ≤ 5 + a/100 mm

Distortion of built up longitudinal,

girder and transverse at upper edge
and flange

+10mm +25mm per 10 m in length

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TABLE 6.3 – Corrugated Bulkheads

Detail Standard Limit Remarks

Mechanical bending
Material to be
suitable for cold
R ≥ 3t mm 2t flanging (forming)
and welding in way
of radius

Depth of corrugation

+ 3mm + 6mm

Breadth of corrugation

+ 3mm + 6mm

h : + 2.5mm H : + 5mm
Pitch and depth of swedged
corrugated bulkhead compared Where it is not aligned with Where it is not aligned
with correct value other bulkheads with other bulkheads
P : + 6mm P : + 9mm

Where it is aligned with Where it is aligned with

other bulkheads other bulkheads
P : + 2mm P : + 3mm

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TABLE 6.4 – Pillars, Brackets and Stiffeners

Detail Standard Limit Remarks

Pillar (between decks)

4 mm 6 mm

Cylindrical structure diameter

(pillars, masts, posts, etc.)

+ D/200 mm + D/150 mm

max. + 5 mm max. 7.5 mm

Tripping bracket and small stiffener,

distortion at the part of free edge

A ≤ t/2 mm t

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TABLE 6.5 - Maximum Heating Temperature on Surface for Line Heating

Item Standard Limit Remarks

Conventional Water cooling just Under 650°C

Process after heating
AH32-EH32 &
AH36-EH36

Air cooling after Under 900°C

TCMP type heating
AH32-EH32 &
AH36-EH36
(Ceq.>0.38%)

Air cooling and Under 900°C (starting

subsequent water temperature of water
cooling after cooling to be under
heating 500°C)

TMCP type Water cooling just Under 1000°C

AH32-DH32 & after heating or air
AH36-DH36 cooling
(Ceq. ≤ 0.38%)

TMCP type Water cooling just Under 900°C

EH32 & EH36 after heating or air
(Ceq. ≤ 0.38%) cooling

NOTE:

Cr + Mo + V Ni + Cu
Ceq = C +
Mn
+ + (% )
6 5 15

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TABLE 6.6 – Block Assembly

Item Standard Limit Remarks

Flat Plate Assembly

Length and Breadth ± 4 mm ± 6 mm

Distortion ±10mm ±20mm

Squareness ±5mm ±10mm

Deviation of interior members from 5mm 10mm

Plate

Curved plate assembly

Length and Breadth ± 4mm ± 8 mm measured along

the girth
Distortion ±10mm ±20mm

Squareness ±10mm ±15mm

Deviation of interior members from 5mm 10mm

plate

Flat cubic assembly

Length and Breadth ± 4mm ± 6 mm

Distortion ±10mm ±20mm

Squareness ±5mm ±10mm

Deviation of interior members from 5mm 10mm

plate

Twist ±10mm ±20mm

Deviation between upper and lower plate ±5mm ±10mm

Curved cubic assembly

Length and Breadth ± 4mm ± 8 mm measured along

with girth
Distortion ±10mm ±20mm

Squareness ±10mm ±15mm

Deviation of interior members from ±5mm ±10mm

plate

Twist ±15mm ±25mm

Deviation between upper and lower plate ±7mm ±15mm

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TABLE 6.7 – Special Sub-Assembly

Item Standard Limit Remarks

Distance between
upper/lower gudgeon ±5mm ±10mm

Distance between aft edge

±5mm ±10mm
of boss and aft peak
bulkhead

Twist of sub-assembly of
stern frame 5mm 10mm

Deviation of rudder from

shaft center line 4mm 8mm

Twist of rudder plate

6mm 10mm

Flatness of top plate of main

engine bed 5mm 10mm

Breadth and length of top

plate of main engine bed ±4mm ± 6mm

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TABLE 6.8 – Shape

Detail Standard Limit Remarks

Deformation for the whole length

per 100 m against the

+ 50 mm
line of keel sighting

Deformation for the distance between two

adjacent bulkheads

+ 15 mm

Cocking-up of fore body

+ 30 mm

Cocking-up of aft-body

+ 20 mm

Rise of floor amidships

+ 15 mm

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TABLE 6.9 – Shape

Item Standard Limit Remarks

Length between perpendiculars ±50 per 100m Applied to ships of

100 metre length and
above.
For the convenience
of the measurement the
point where the keel is
connected to the curve of
the stern may be
substituted for the fore
perpendicular in the
measurement of the length.

Length between aft edge of boss and ±25mm

main engine

Moulded breadth at midship ±15mm Applied to ships of 15

metre breadth and above.
Measured on the upper
deck.

Moulded depth at midship ±10mm Applied to ships of

10 metre depth and above.

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TABLE 6.10 – Fairness of Plating Between Frames

Item Standard Limit Remarks

Parallel part
4mm
(side & bottom shell)
Shell plate

Fore and aft part 5mm

8mm
Tank top plate 4mm

Longl. Bulkhead
Bulkhead
Trans. Bulkhead 6mm
Swash Bulkhead

Parallel part 4mm 8mm

Strength deck Fore and aft part 6mm 9mm

Covered part 7mm 9mm

Bare part 6mm 8mm

Second deck
Covered part 7mm 9mm

Forecastle deck Bare part 4mm 8mm

poop deck
Covered part 6mm 9mm

Super structure Bare part 4mm 6mm

Deck
Covered part 7mm 9mm

Outside wall 4mm 6mm

House wall Inside wall 6mm 8mm

Covered part 7mm 9mm

Interior member (web of girder, etc) 5mm 7mm

Floor and girder in double bottom 5mm 7mm

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TABLE 6.11 – Fairness of Plating with Frames

Item Standard Limit Remarks

Parallel part ±2 l /1000mm ±3 l /1000mm

Shell plate
Fore and aft part ±3 l /1000mm ±4 l /1000mm
l = span of frame

Strength deck - ±3 l /1000mm ±4 l /1000mm

(excluding To be measured
cross deck) and between on trans.
top plate of space (min. l = 3m)
double bottom

Bulkhead - ±4 l /1000mm ±5 l /1000mm

Others - ±5 l /1000mm ±6 l /1000mm

l = span of frame
(minimum l =3m)

To be measured between one

trans. space.

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TABLE 6.12 – Preheating for welding hull steels at low temperature

Standard Limit Remarks

Item
Base metal Minimum
temperature needed preheating
preheating temperature

Normal strength
A, B, D, E Below -5oC
steels

Higher strength
steels Below 0oC
(TMCP type) 20oC 1)

AH32 – EH 32
AH36 – EH 36

Higher strength
steels
Below 5 oC
(Conventional
type)

(Note)
1) This level of preheat is to be applied unless the approved welding procedure specifies a higher level.

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TABLE 7.1 – Alignment

Detail Standard Limit Remarks

Alignment of butt welds

a ≤ 0.15t strength a ≤ 3.0 mm

a ≤ 0.2t other

a) Strength and higher a) Strength and higher

tensile: tensile:
a ≤ t1/4 a ≤ t1/3
Alignment of fillet welds measured on the measured on the
median. median.
or or
a1 ≤ (3t1- 2t2)/4 a1 ≤ t1/3
measured on the measured on the
heel line. heel line. Where t3 is less than
t1 , then t3 should be
b) Other: b) Other: substituted for t1 in
a ≤ t1/3 a≤ t1/2 the standard.
measured measured on the
on the median. median.
or or
a1 ≤ (5t1- 3t2)/6 a1 ≤ t1/2
t1 < t2 measured on the measured on the
heel line. heel line.

Alignment of fillet welds

t2 a) Strength and higher a)Strength and higher
tensile: tensile:
a ≤ t1/4 measured a ≤ t1/3 measured
on the median on the median
or or
t3 a1 ≤ (3t1- 2t2)/4 a1 ≤ t1/3
measured on the measured on the
Where t3 is less
heel line. heel line.
than t1, then t3
should be substitute
b) Other: b) Other:
for t1 in the standard.
a ≤ t1/3 a ≤ t1/2
measured measured on the
on the median median
or or
a1 ≤ (5t1- 3t2)/6 a1 ≤ t1/2
measured on the measured on the
heel line. heel line.

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TABLE 7.2 – Alignment

Detail Standard Limit Remarks

Alignment of flange of T-longitudinal

a ≤ 0.04b strength a = 8.0 mm

Alignment of height of T-bar, L-angle bar or

bulb
Primary members
a ≤ 0.15t
a = 3.0 mm
Secondary members
a ≤ 0.20t

Alignment of panel stiffener

d ≤ L/50

Gap between bracket/intercostal and

Stiffener

a ≤ 2.0 mm a = 3.0 mm

Alignment of lap welds

a ≤ 2.0 mm a = 3.0 mm

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TABLE 7.3 – Alignment

Detail Standard Limit Remarks

Gap between beam and frame

a ≤ 2.0 mm a = 5.0 mm

Gap around stiffener cut-out

s ≤ 2.0 mm s = 3.0 mm

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TABLE 8.1 –Typical Butt Weld Plate Edge Preparation (Manual Welding)

Detail Standard Limit Remarks

Square butt

t ≤ 5 mm G = 5mm see Note 1

G ≤ 3 mm

Single level butt

t > 5 mm G = 5mm see Note 1

G ≤ 3 mm

Double bevel butt

t > 19 mm G = 5mm see Note 1

G ≤ 3 mm

Double vee butt, uniform bevels

G ≤ 3 mm G = 5mm see Note 1

Double vee butt, non-uniform bevel

G ≤ 3 mm G = 5mm see Note 1

NOTE 1

Different plate edge preparation may be accepted or approved by the Classification Society on the basis of an
appropriate welding procedure specification.
For welding procedures other than manual welding, see paragraph 3.2 Qualification of weld procedures.

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TABLE 8.2 – Typical Butt Weld Plate Edge Preparation (Manual Welding)

Detail Standard Limit Remarks

Single vee butt, one side welding with

backing strip (temporary or permanent)

G = 3 - 9 mm G = 16mm see Note 1

Single vee butt

G ≤ 3 mm G = 5mm see Note 1

NOTE 1

Different plate edge preparation may be accepted or approved by the Classification Society on the basis of an
appropriate welding procedure specification.
For welding procedures other than manual welding, see paragraph 3.2 Qualification of welding procedures.

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Table 8.3 - Typical Fillet Weld Plate Edge Preparation (Manual Welding)

Detail Standard Limit Remarks

Tee Fillet

G ≤ 2 mm G = 3mm
see Note 1

Small angle fillet

see Note 1
G ≤ 2 mm G = 3mm

Single bevel tee with permanent backing

Not normally for

strength
G ≤ 4 - 6 mm
G = 16mm members
θ° = 30° - 45°
also see Note 1

Single bevel tee

see Note 1
G ≤ 3 mm

NOTE 1

Different plate edge preparation may be accepted or approved by the Classification Society on the basis of an
appropriate welding procedure specification.
For welding procedures other than manual welding, see paragraph 3.2 Qualification of welding procedures.

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Table 8.4 Typical Fillet Weld Plate Edge Preparation (Manual Welding)

Detail Standard Limit Remarks

Single ‘J’ tee

G =2.5 - 4 mm see Note 1

Double bevel tee symmetrical

t > 19 mm
G ≤ 3 mm see Note 1

Double bevel tee assymetrical

see Note 1
t > 19 mm
G ≤ 3 mm

Double J bevel symmetrical

G =2.5- 4 mm see Note 1

NOTE 1
Different plate edge preparation may be accepted or approved by the Classification Society on the basis of an
appropriate welding procedure specification.
For welding procedures other than manual welding, see paragraph 3.2 Qualification of welding procedures.

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Table 8.5 Typical Butt And Fillet Weld Profile (Manual Welding)

Detail Standard Limit Remarks

Butt weld toe angle

θ ≤ 60° θ ≤ 90°
h ≤ 6mm

Butt weld undercut

0.5 mm

Fillet weld leg length

s = leg length s ≥ 0.9sd sd= design s

a = throat depth a ≥ 0.9ad ad= design a

over short weld

lengths

Fillet weld toe angle

In areas of stress
concentration
and fatigue, the
θ ≤ 90°
Class Society
may require a
lesser angle.

Fillet weld undercut

0.5 mm

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Table 8.6 Distance Between Welds

Detail Standard Limit Remarks

Scallops over weld seams

for significant The “d” is to be

members measured from the
d ≥ 5mm toe of the fillet weld
to the toe of the butt
for other members weld.
r d ≥ 0mm

Distance between two butt welds

d ≥ 0 mm

Distance between butt weld and fillet weld

for significant
members

d ≥ 10 mm

for other members

d ≥ 0 mm

Distance between butt welds

for cut-outs
d ≥ 30 mm

for margin plates 150 mm

d ≥ 300 mm

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Table 8.7 - Automatic Welding

Detail Standard Limit Remarks

Submerged Arc Welding (SAW)

Edge preparation as
per Tables 8.1 and
8.2

0 ≤ G ≤ 0.8 mm G = 2 mm SAW may follow

WPS approved by
the Classification
Society.

See Note 1.

NOTE 1

Different plate edge preparation may be accepted or approved by the Classification Society on the basis of an
appropriate welding procedure specification.
For welding procedures other than manual welding, see paragraph 3.2 Qualification of welding procedures.

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Table 9.1 - Typical Misalignment Repair

Detail Repair Standard Remarks

t1 is lesser plate thickness
Alignment of butt joints a) Strength members
a > 0.15t1 or a > 3 mm
release and adjust

b) Others
a > 0.2t1 or a > 3 mm
release and adjust

Where t3 is less than t1 then t3

Alignment of fillet welds a) Strength and higher tensile steel should be substituted for t1 in
t1/3 < a ≤ t1/2 - generally increase weld standard
throat by 10%

a > t1/2 - release and adjust over a

minimum of 50a

b) Others
a > t1/2 - release and adjust over a
minimum of 30a

Alignment of flange of T-longitudinal When 0.04b < a ≤ 0.08b, max 8 mm:

grind corners to smooth taper over a
minimum distance L = 3a

When a > 0.08b or 8 mm:

grind corners to smooth taper over a
minimum distance L=50a

Alignment of height of T-bar, L-angle When 3 mm < a ≤ 6 mm:

bar or bulb building up by welding

When a > 6 mm:

release and adjust over minimum L = 50a
for primary structure and L = 30a
elsewhere

Alignment of lap welds

3 mm < a ≤ 5 mm:
weld leg length to be increased by the same
amount as increase in gap

a > 5 mm:
members to be re-aligned

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Table 9.2 - Typical Misalignment Repair

Detail Repair Standard Remarks

Gap between bracket/intercostal When 3 mm < a ≤ 5mm:

and stiffener weld leg length to be increased by increase
in gap

When 5mm < a ≤ 10mm:

chamfer 30° - 40° and build up with
welding

When a > 10mm:

increase gap to 50mm and fit collar plate

b= (2t + 25)mm, min. 50mm

Gap between beam and frame

a > 3 mm release and adjust

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TABLE 9.3 – Misalignment Repair

Detail Repair standard Remarks

Position of scallop When d < 75mm

web plate to be cut between scallop and slot,
and collar plate to be fitted

OR fit small collar over scallop

d

OR fit collar plate over scallop

Gap around stiffener cut-out When 3 mm < s ≤ 5mm

weld leg length to be increased as much as
increase in gap opening over 2mm

When 5 mm < s ≤ 10 mm
nib to be chamfered and built up by welding

When s > 10mm

cut off nib and fit collar plate with same
height as nib

20 mm ≤ b ≤ 50mm

- 32 -
TABLE 9.4 – Typical Butt Weld Plate Edge Preparation Repair (Manual Welding)

Detail Repair standard Remarks

Square butt When G ≤ 10 mm

chamfer to 45゜and build up by welding

When G > 10mm

build up with backing strip; remove,
back gouge and seal weld;
or, insert plate, min. width 300 mm

Single bevel butt

When 5 mm < G ≤ 16 mm

build up gap with welding on one or both sides of

preparation, with possible use of backing strip as
necessary, to maximum 16 mm.

Where a backing strip is used, the backing strip is

to be removed, the weld back gouged, and a
sealing weld made.

Different welding procedure by using other

backing material approved by the Classification
Double bevel butt Society may be accepted on the basis of an
appropriate welding procedure specification.

max. 16mm

When 16mm < G < 25mm

Welding up with edge preparation or partly renew
Double vee butt, uniform bevels welding

When G > 25mm

An insert plate, of minimum width 300mm, to
welded in place.

Double vee butt, non-uniform bevel

- 33 -
TABLE 9.5 – Typical Butt Weld Plate Edge Preparation Repair (Manual Welding)

Detail Repair Standard Remarks

Single vee butt, one side welding When 5 mm < G ≤ 16 mm

build up gap with welding on
one or both sides of preparation, with
possible use of backing strip as
necessary, to maximum 16mm.

Where a backing strip is used, the backing

strip is to be removed, the weld back
gouged, and a sealing weld made.

Different welding procedure by using other

backing material approved by the
Classification Society may be accepted on
the basis of an appropriate welding
Single vee butt procedure specification.

max. 16mm

When 16mm < G < 25mm

Welding up with edge preparation or partly
renew welding.

When G > 25 mm
an insert plate, of minimum width
300 mm, to be welded in place.

- 34 -
TABLE 9.6 – Typical Fillet Weld Plate Edge Preparation Repair (Manual Welding)

Detail Repair standard Remarks

Tee Fillet 3 mm < G ≤ 5mm – leg length increased

to Rule leg + (G-2)

5 mm < G ≤ 16 mm or G ≤ 1.5t - chamfer to

30° to 45°,
build up with welding, on one side, with or
without backing strip, grind and weld.

G > 16 mm or G > 1.5t - new plate to be

inserted (min. 300mm)

Liner treatment

t2 ≤ t ≤ t1 Not to be used in
G ≤ 2mm cargo area or areas
a = 5 mm + fillet leg length of tensile stress
perpendicular to
liner

- 35 -
TABLE 9.7 – Typical Fillet Weld Plate Edge Preparation Repair (Manual Welding)

Detail Repair standard Remarks

Single bevel tee 3 mm < G ≤ 5mm

build up weld

5 mm < G ≤ 16 mm - build up with

welding, with or without backing strip,
remove backing strip if used, back
gouge and back weld.

G > 16mm new plate to be inserted of

minimum width 300mm

- 36 -
TABLE 9.8 –Typical Fillet Weld Plate Edge Preparation Repair (Manual Welding)

Detail Repair standard Remarks

Single ’J’ tee as single bevel tee

Double bevel tee symmetrical

When 3 mm < G ≤ 16 mm build up with

welding using ceramic or other approved
backing bar, remove, back gouge and back
weld.

Double bevel tee asymmetrical

When G > 16 mm-insert plate of minimum

height 300 mm to be fitted.

Double J bevel symmetrical

- 37 -
TABLE 9.9 – Typical Fillet and Butt Weld Profile Repair (Manual Welding)

Detail Repair standard Remarks

Fillet weld leg length

Increase leg or throat by welding over

Minimum short bead

H.T. (Ceq > 0.36%);
Fillet weld toe angle Length ≥ 50mm
H.T. (Ceq ≤ 0.36%);
Length ≥ 30mm

θ > 90° grinding, and welding, where

necessary, to make θ < 90°

Butt weld toe angle

θ > 90° grinding, and welding, where

necessary, to make θ < 90°

Butt weld undercut

Where 0.5 < D ≤ 1 mm

undercut to be ground smooth (localized
only)

Fillet weld undercut

Where D > 1 mm
undercut to be filled by welding

- 38 -
TABLE 9.10 – Distance Between Welds Repair

Detail Repair standard Remarks

Scallops over weld seams

Hole to be cut and ground smooth to

obtain distance

- 39 -
TABLE 9.11 – Erroneous Hole Repair

Detail Repair standard Remarks

Holes made erroneously D < 200 mm Strength members

open hole to minimum 75 mm dia.,
fit and weld spigot piece

Fillet weld to be made

after butt weld

1/2 t t1 t
l = 50 mm
The fitting of spigot
OR pieces in areas of high
open hole to over 200 mm and fit insert plate stress concentration or
fatigue is to be approved
by the Classification
Other members Society.
open hole to over 200 mm and fit insert plate

OR fit lap plate

t1 = t2 L = 50 mm, min

Holes made erroneously D ≥ 200 Strength members

mm open hole and fit insert plate

Other members

open hole to over 300 mm and fit insert plate

OR fit lap plate

t1 = t2 L = 50 mm, min

- 40 -
TABLE 9.12 – Repair by Insert Plate

Detail Repair standard Remarks

Repair by insert plate

L = 300 mm minimum

B = 300 mm minimum

R = 5t mm
100mm minimum

(1) seam with insert piece is to be welded

first

(2) original seam is to be released and

welded over for a minimum of 100mm.

Repair of built section by insert plate

L min ≥ 300 mm

Welding sequence
(1) →(2) →(3) →(4)

Web butt weld scallop to be filled during

final pass (4)

- 41 -
TABLE 9.13 – Weld Surface Repair

Detail Repair standard Remarks

Weld spatter 1. Remove spatter observed before In principal, no grinding is

blasting with scraper or chipping applied to weld surface.
hammer, etc.

2. For spatter observed after blasting:

a) Remove with a chipping hammer,
scraper, etc.
b) For spatter not easily removed with
a chipping hammer, scraper, etc.,
grind the sharp angle of spatter to
make it obtuse.

Arc strike Remove the hardened zone by grinding

or other measures such as overlapped weld
bead etc.

- 42 -
___________________________________________________________________________

Part B Repair Quality Standard

for Existing Ships
___________________________________________________________________________
PART B -SHIPBUILDING AND REPAIR QUALITY STANDARD FOR EXISTING SHIPS

CONTENTS:

1. Scope
2. General requirements to repairs and repairers
3. Qualification of personnel
3.1 Qualification of welders
3.2 Qualification of welding procedures
3.3 Qualification of NDE operators
4. Materials
4.1 General requirements to materials
4.2 Equivalency of material grades
5. General requirements to welding
5.1 Correlation of welding consumables to hull structural steels
5.2 General requirements to preheating and drying out
5.3 Dry welding on hull plating below the waterline of vessels afloat
6. Repair quality standard
6.1 Welding, general
6.2 Renewal of plates
6.3 Doubler on plates
6.4 Renewal of internals/stiffeners
6.5 Renewal of internals/stiffeners - transitions inverted angles/bulb profiles
6.6 Termination of straps
6.7 Welding of pitting corrosion
6.8 Welding repairs of cracks
6.9 Grinding of shallow cracks

REFERENCES

1. IACS “Bulk Carriers - Guidelines for Surveys, Assessment and Repair of Hull Structure”
2. TSCF “Guidelines for the inspection and maintenance of double hull tanker structures”
3. TSCF “Guidance manual for the inspection and condition assessment of tanker structures”
4. IACS UR W 11 “Normal and higher strength hull structural steels”
5. IACS UR W 13 “Allowable under thickness tolerances of steel plates and wide flats”
6. IACS UR W 17 “Approval of consumables for welding normal and higher strength hull structural steels”
7. IACS Z 10.1 “Hull surveys of oil tankers” and Z 10.2 “Hull surveys of bulk carriers” Table IV
8. IACS UR Z 13 “Voyage repairs and maintenance”
9. IACS Recommendation 12 “Guidelines for surface finish of hot rolled steel plates and wide flats”
10. IACS Recommendation 20 “Guide for inspection of ship hull welds”

1. Scope

1.1 This standard provides guidance on quality of repair of hull structures. The standard covers permanent
repairs of existing ships.

Whereas the standard generally applies to

- conventional ship types,
- parts of hull covered by the rules of the Classification Society,
- hull structures constructed from normal and higher strength hull structural steel,
the applicability of the standard is in each case to be agreed upon by the Classification Society.

The standard does generally not apply to repair of

- special types of ships as e.g. gas tankers
- structures fabricated from stainless steel or other, special types or grades of steel
1.2 The standard covers typical repair methods and gives guidance on quality standard on the most important
aspects of such repairs. Unless explicitly stated elsewhere in the standard, the level of workmanship reflected
herein will in principle be acceptable for primary and secondary structure of conventional design. A more
stringent standard may however be required for critical and highly stressed areas of the hull, and is to be agreed
with the Classification Society in each case. In assessing the criticality of hull structure and structural
components, reference is made to ref. 1, 2 and 3.

1.3 Restoration of structure to the original standard may not constitute durable repairs of damages originating
from insufficient strength or inadequate detail design. In such cases strengthening or improvements beyond the
original design may be required. Such improvements are not covered by this standard, however it is referred to
ref. 1, 2 and 3.

2. General requirements for repairs and repairers

2.1 In general, when hull structure covered by classification is to be subjected to repairs, the work is to be carried
out under the supervision of the Surveyor to the Classification Society. Such repairs are to be agreed prior to
commencement of the work.

2.2 Repairs are to be carried out by workshops, repair yards or personnel who have demonstrated their capability
to carry out hull repairs of adequate quality in accordance with the Classification Society’s requirements and this
standard.

2.3 Repairs are to be carried out under working conditions that facilitate sound repairs. Provisions are to be made
for proper accessibility, staging, lighting and ventilation. Welding operations are to be carried out under shelter
from rain, snow and wind.

2.4 Welding of hull structures is to be carried out by qualified welders, according to approved and qualified
welding procedures and with welding consumables approved by the Classification Society, see Section 3. Welding
operations are to be carried out under proper supervision of the repair yard.

2.5 Where repairs to hull which affect or may affect classification are intended to be carried out during a voyage,
complete repair procedure including the extent and sequence of repair is to be submitted to and agreed upon by
the Surveyor to the Classification Society reasonably in advance of the repairs. See Ref. 8.

3. Qualification of personnel

3.1 Qualification of welders

3.1.1 Welders are to be qualified in accordance with the procedures of the Classification Society or to a recognised
national or international standard, e.g. EN 287, ISO 9606, ASME Section IX, ANSI/AWS D1.1. Recognition of
other standards is subject to submission to the Classification Society for evaluation. Repair yards and workshops
are to keep records of welders qualification and, when required, furnish valid approval test certificates.

3.1.2 Welding operators using fully mechanised of fully automatic processes need generally not pass approval
testing, provided that production welds made by the operators are of the required quality. However, operators are
to receive adequate training in setting or programming and operating the equipment. Records of training and
production test results shall be maintained on individual operator’s files and records, and be made available to the
Classification Society for inspection when requested.

3.2 Qualification of welding procedures

Welding procedures are to be qualified in accordance with the procedures of the Classification Society or a
recognised national or international standard, e.g. EN288, ISO 9956, ASME Section IX, ANSI/AWS D1.1.
Recognition of other standards is subject to submission to the Classification Society for evaluation. The welding
procedure should be supported by a welding procedure qualification record. The specification is to include the
welding process, types of electrodes, weld shape, edge preparation, welding techniques and positions
3.3 Qualification of NDE operators
3.3.1 Personnel performing non destructive examination for the purpose of assessing quality of welds in
connection with repairs covered by this standard, are to be qualified in accordance with the Classification Society
rules or to a recognised international or national qualification scheme. Records of operators and their current
certificates are to be kept and made available to the Surveyor for inspection.

4. Materials

4.1. General requirements for materials

4.1.1 The requirements for materials used in repairs are in general the same as the requirements for materials
specified in the Classification Society’s rules for new constructions, (ref. 5)

4.1.2 Replacement material is in general to be of the same grade as the original approved material. Alternatively,
material grades complying with recognised national or international standards may be accepted by the
Classification Societies provided such standards give equivalence to the requirements of the original grade or are
agreed by the Classification Society. For assessment of equivalency between steel grades, the general requirements
and guidelines in Section 4.2 apply.

4.1.3 Higher tensile steel is not to be replaced by steel of a lesser strength unless specially approved by the
Classification Society.

4.1.4 Normal and higher strength hull structural steels are to be manufactured at works approved by the
Classification Society for the type and grade being supplied.

4.1.5 Materials used in repairs are to be certified by the Classification Society applying the procedures and
requirements in the rules for new constructions. In special cases, and normally limited to small quantities,
materials may be accepted on the basis of alternative procedures for verification of the material’s properties. Such
procedures are subject to agreement by the Classification Society in each separate case.

4.2. Equivalency of material grades

4.2.1 Assessment of equivalency between material grades should at least include the following aspects;
- heat treatment/delivery condition
- chemical composition
- mechanical properties
- tolerances

4.2.2 When assessing the equivalence between grades of normal or higher strength hull structural steels up to
and including grade E40 in thickness limited to 50 mm, the general requirements in Table 4.1 apply.

4.2.3 Guidance on selection of steel grades to certain recognised standards equivalent to hull structural steel
grades specified in Classification Societies’ rules is given in Table 4.2

5. General requirements to welding

5.1 Correlation of welding consumables with hull structural steels

5.1.1 For the different hull structural steel grades welding consummables are to be selected in accordance with
IACS UR W17 (see Ref.5).

5.2 General requirements to preheating and drying out

5.2.1 The need for preheating is to be determined based on the chemical composition of the materials, welding
process and procedure and degree of joint restraint.

5.2.2 A minimum preheat of 50o C is to be applied when ambient temperature is below 0°C. Dryness of the
welding zone is in all cases to be ensured.
5.2.3 Guidance on recommended minimum preheating temperature for higher strength steel is given in Table 5.1.
For automatic welding processes utilising higher heat input e.g. submerged arc welding, the temperatures may be
reduced by 50o C. For re-welding or repair of welds, the stipulated values are to be increased by 25 o C.

Items to be Requirements Comments

considered
Chemical - C; equal or lower The sum of the elements, e.g. Cu, Ni, Cr and Mo
composition - P and S; equal or lower should not exceed 0.8%
- Mn; approximately the same but
not exceeding 1.6%
- Fine grain elements; in same
amount
- Deoxidation practice

Mechanical - Tensile strength; equal or higher Actual yield strength should not exceed
properties - Yield strength; equal or higher Classification Society Rule minimum
- Elongation; equal or higher requirements by more than 80 N/mm2
- Impact energy; equal or higher at
same or lower temperature, where
applicable

Condition of Same or better Heat treatment in increasing order;

supply - as rolled (AR)
- controlled rolled (CR)
- normalised (N)
- thermo-mechanically rolled (TM)1)
- quenched and tempered (QT)1)
1) TM- and QT-steels are not suitable for
hot forming
Tolerances - Same or stricter Permissible under thickness tolerances;
- plates: 0.3 mm
- sections: according to recognised
standards

Table 4.1 Minimum extent and requirements to assessment of equivalency between normal or higher
strength hull structural steel grades

5.3 Dry welding on hull plating below the waterline of vessels afloat

5.3.1. Welding on hull plating below the waterline of vessels afloat is acceptable only on normal and higher
strength steels with specified yield strength not exceeding 355 MPa and only for local repairs. Welding involving
other high strength steels or more extensive repairs against water backing is subject to special consideration and
approval by the Classification Society of the welding procedure.

5.3.2. Low-hydrogen electrodes or welding processes are to be used when welding on hull plating against water
backing. Coated low-hydrogen electrodes used for manual metal arc welding should be properly conditioned to
ensure a minimum of moisture content.

5.3.3 In order to ensure dryness and to reduce the cooling rate, the structure is to be preheated by a torch or
similar prior to welding, to a temperature of minimum 5oC or as specified in the welding procedure.
 Table 4.2 Guidance on steel grades comparable to the normal and high strength hull structural steel grades given in Classification Society rules

Steel grades according to Classification Societies’ rules (ref. 5) Comparable steel grades

Yield Tensile Elongation Average impact ISO EN ASTM JIS

stress strength energy 630-80
Grade ReH Rm A5 Temp. J, min. 4950/2/3 EN 10025-93 A 131 G 3106
min. min. 1981 EN 10113-93
N/mm2 N/mm2 % °C L T
A +20 - - Fe 360B S235JRG2 A SM41B
B 0 27 20 Fe 360C S235J0 B SM41B
D 235 400 - 502 22 -20 27 20 Fe 360D S235J2G3 D (SM41C)
E -40 27 20 - S275NL/ML E -
A 27 0 Fe 430C S275J0G3 - -
D 27 265 400 - 530 22 -20 27 20 Fe 430D S275N/M - -
E 27 -40 - S275NL/ML - -
A 32 0 - - AH32 SM50B
D 32 -20 - - DH32 (SM50C)
315 440 - 590 22 31 22 - -
E 32 -40 EH32 -
A 36 0 Fe 510C S355N/M AH36 SM53B
D 36 -20 Fe 510D S355N/M DH36 (SM53C)
355 490 - 620 21 34 24 E355E S355NL/ML
E 36 -40 EH36 -
A 40 0 E390CC S420N/M AH40 (SM58)
D 40 -20 E390DD S420N/M DH40 -
390 510 - 650 20 41 27 E390E S420NL/ML
E 40 -40 EH40 -

Note : In selecting comparable steels from this table, attention should be given to the requirements of Table 4.1 and the dimension requirements of the product with respect
to Classification Society rules.
Carbon equivalent Recommended minimum preheat temperature ( 0 C )
tcomb ≤ 50 mm 2) 50 mm<tcomb ≤ 70 mm 2)
1)
tcomb >70 mm 2)
Ceq ≤ 0.39 - - 50
Ceq ≤ 0.41 - - 75
Ceq ≤ 0.43 - 50 100
Ceq ≤ 0.45 50 100 125
Ceq ≤ 0.47 100 125 150
Ceq ≤ 0.50 125 150 175

Table 5.1 Preheating temperature

NOTES
Mn Cr + Mo + V Ni + Cu
1) Ceq = C + + + (%)
6 5 15
2) Combined thickness tcomb = t1 + t2 + t3 + t4 , see figure

t3
= =

t1 t2 t1 t2
t4
6. Repair quality standard

6.1 Welding, general

Fig. 6.1 Groove roughness

Item Standard Limit Remarks

Material Grade Same as original or See Section 4
higher

Welding Consumables IACS UR-W17 Approval according. to

(ref. 6) equivalent
international standard
Groove / roughness See note and Fig. 6.1 d < 1.5 mm Grind smooth

Pre-Heating See Table 5.1 Steel temperature not

lower than 5oC
Welding with water on See Section 5.3 Acceptable for normal -Moisture to be
the outside and high strength removed by a heating
steels torch
Alignment As for new
construction

Weld finish IACS guide for

inspection of ship hull
welds (ref. 10)
NDE IACS guide (ref. 10) At random with extent
to be agreed with
attending surveyors

NOTE :
Slag, grease, loose mill scale, rust and paint, other than primer, to be removed.
6.2 Renewal of plates

3
2 3

1 2
R

4 1

R = 5 x plate thickness 4
100mm 100mm
min. 100mm

Fig 6.2 Welding sequence for inserts

Item Standard Limit Remarks

Size insert Min. 300x300mm Min. 200x200mm
R = 5 x thickness Min R = 100 mm
Circular inserts:
Dmin=200mm

Material grade Same as original or See Section 4.

higher

Edge Preparation As for new In case of non

construction compliance increase
the amount of NDE
Welding sequence See fig.6.2 For primary members
Weld sequence is sequence 1 and 2
1→ 2 → 3 → 4 transverse to the main
stress direction
Alignment As for new
construction

Weld finish IACS guide for

inspection of ship hull
welds (ref. 10)
NDE IACS guide (ref. 10)
6.3 Doublers on plating

Local doublers are normally only allowed as temporary repairs, except as original compensation for openings,
within the main hull structure.

ld

Slot weld throat

R

Pitch
t

Size of
slot

Fig. 6.3 Doublers on plates

Item Standard Limit Remarks

Existing plating General: t > 5 mm For areas where
existing plating is less
than 5mm plating a
permanent repair by
insert is to be carried
out.
Extent/size Rounded off corners. min 300x300mm
R > 50mm

Thickness of doubler (td) td ≤ tp (tp = original td > tp/3

thickness of existing
plating )
Material grade Same as original plate See Section 4

Edge preparation As for [newbuilding] Doublers welded on

new construction primary strength
members: (Le: leg
length)
when t > Le + 5mm,
the edge to be tapered
(1:4)
Welding As for [newbuilding] Welding sequence
new construction similar to insert plates.
Weld size(throat thickness) Circumferencial and in
slots: 0.6 x td
Slot welding Normal size of slot: Max pitch between For doubler extended
(80-100) x 2 td slots 200mm over several supporting
elements, see figure 6.3
Distance from doubler
edge and between slots: dmax = 500mm
d < 15 td
NDE IACS
Recommendation 20
( Ref. 10)
6.4 Renewal of internals/stiffeners

Min. size of insert

Release fillet weld over

a distance d prior to
welding sector 3 2 1

d d

Fig 6.4 Welding sequence for inserts of stiffeners

Item Standard Limit Remarks

Size insert Min. 300 mm Min. 200mm

Material grade Same as original or See Section 4.

higher

Edge Preparation As for new

construction.
Fillet weld stiffener
web/plate to be released
over min. d = 150 mm

Welding sequence See fig.6.4 .

Weld sequence is
1→ 2 → 3

Alignment As for new

construction

Weld finish IACS guide for

inspection of ship hull
welds (ref. 10)
NDE IACS guide (ref. 10)
6.5 Renewal of internals/stiffeners - transitions inverted angle/bulb profile

The application of the transition is allowed for secondary structural elements.

b1
h1
1:4

t1
15o
=

t2
l

tf 15o

bf
=

h2

tf2
1:4

b2 Transition angle

Fig. 6.5 Transition between inverted angle and bulb profile

Item Standard Limit Remarks

(h1 - h2) < 0.25 x b1

| t1 - t2| 2 mm Without tapering

transition.
Transition angle 15 degrees At any arbitrary section

Flanges tf = tf2
bf = bf2
Length of flatbar 4 x h1

Material See Section 4.

6.6 Termination of straps

Assymmetrical arrangement

R
Strap t b
Increased throat
thickness
Taper /b > 3
Symmetrical arrangement
Increased throat
thickness

Strap t b
Taper /b > 3
Fig. 6.6 Termination of straps

Item Standard Limit Remarks

Tapering /b > 3 Special consideration
to be drawn to design
of strap terminations in
Radius 0.1 x b min 30mm fatigue sensitive areas.
Material See paragraph 2.0
General requirement to
materials.
Weld size Depending on number
and function of straps.
Throat thickness to be
increased 15 % toward
ends.
Welding Welding sequence See sketch. For
from middle towards welding of lengths >
the free ends 1000mm step welding
to be applied.
6.7 Welding of pitting corrosion

NOTES:
Shallow pits may be filled by applying coating or pit filler. Pits can be defined as shallow when their depth is less
than 1/3 of the orginal plate thickness.

Welding direction

Grind flush
Finish outside pit Start outside pit

Fig. 6.7 Welding of pits

Item Standard Limit Remarks

Extent/depth Pits/grooves are to be If deep pits or grooves See also IACS
welded flush with the are clustered together Recommendation 12
original surface. or remaining thickness ( Ref.9)
is less than 6 mm, the
plate should be
renewed.
Cleaning Heavy rust to be
removed
Pre-Heating See Table 5.1 Required when Always use propane
ambient torch or similar to
temperature < 5oC remove any moisture
Welding sequence Reverse direction for See also IACS guide
each layer no. 12
Weld finish IACS guide for
inspection of ship hull
welds (ref. 10)
NDE IACS guide (ref. 10) Min. 10% extent Preferably MPI

Reference is made to TSCF Guidelines, Ref. 2 & 3.

6. 8 Welding repairs for cracks

Tab
3 2 1

Fig. 6.8.a Step back technique Fig 6.8.b End crack termination

3 2 1

Fig 6.8.c Welding sequence for cracks with length less than 300 mm
θo

R
Fig. 6.8.d Groove preparation
(U-groove left and V-groove right)

Item Standard Limit Remarks

Groove preparation θ=45-60o For through plate cracks as
r= 5 mm for newbuilding. Also see
fig 6.8.d
Termination Termination to have For cracks ending on edges
slope 1:3 weld to be terminated on a
tab see Fig 6.8.b
Extent On plate max. 400 mm On plate max 500
length. Vee out 50 mm mm. Linear crack,
past end of crack not branched
Welding sequence See fig 6.8.c for For cracks longer Always use low hydrogen
sequence and direction than 300 mm step- welding consumables
back technique
should be used Fig
6.8.a
Weld finish IACS guide for
inspection of ship hull
welds (ref. 10)
NDE IACS guide (ref.10) 100 % MP or PE of 100 % surface crack
groove detection + UE or RE for
butt joints
6.9 Grinding of shallow cracks

Disk grinder Rotary burr grinder

Main stress direction

Final grinding direction Max. grinding

depth

Fig 6.9 Grinding

Item Standard Limit Remarks

Extent For short cracks only See also IACS
max. 4 t Max. length recommendation 12,
t = Plate thickness 100 mm (ref. 9)

Grinding direction Final grinding Grinding always to be

microgrooves parallel finished by a rotating
to main stress direction burr and not a disk
grinder

Grinding depth Max. 0.2 t Always smooth

t = Plate thickness transition
NDE IACS guide for 100 % MPI
inspection of ship hull
welds (ref. 10)