INDIAN REGISTER OF SHIPPING
CLASSIFICATION NOTES
Guidelines for Non-
Destructive Examination of
Steel Castings for Marine
Application
January 2005
Guidelines for Non-Destructive Examination of Steel Castings for Marine Application –
January 2005
Page 2 of 17
CLASSIFICATION NOTES
Guidelines for Non-Destructive Examination of
Steel Castings for Marine Application
January 2005
Contents
Sections
1. General
1.1 Scope
2. Personnel Requirements
2.1 Qualifications
3. Casting Condition
3.1 Heat Treatment
3.2 Surface Condition
4. Extent of Examinations
4.1 Castings to be examined
4.2 Zones to be examined
5. Examination Procedures
5.1 Visual Inspections
5.2 Surface Crack Detection
5.3 Volumetric Inspections
6. Acceptance Criteria
6.1 Visual Testing
6.2 Surface Crack Detection
6.3 Volumetric Testing
7. Reporting
8. Rectification of Defects
Classification Notes Indian Register of Shipping
Guidelines for Non-Destructive Examination of Steel Castings for Marine Application –
January 2005
Page 3 of 17
1. General
1.1 Scope
1.1.1 These guidelines complement the requirements for hull and machinery
steel castings given in IRS Rules Pt.2, Ch.4 “Steel Castings” and in
Pt.4, Ch.4 “Prime Movers and Propulsion Shafting systems” and
contain general guidance on the extent, methods and recommended
quality levels applicable to the non-destructive examinations (NDE), of
marine steel castings, except in those cases where alternative criteria
have been otherwise approved or specified.
1.1.2 The requirements in these guidelines may also be applied for other
machinery components, giving due consideration to their materials,
types, shapes and stress conditions etc.
2. Personnel Requirements
2.1 Qualifications
2.1.1 Personnel carrying out NDE are to be qualified and certified to at least
Level II of a recognised certification scheme such as EN 473, ISO 9712
or ASNT-TC-1A/ ISNT.
2.1.2 Personnel responsible for the NDE activity including approval of
procedures are to be qualified and certified to Level III of ISNT/ASNT.
3. Casting Condition
3.1 Heat Treatment
3.1.1 Non-destructive examinations applied for acceptance purposes are to
be made after the final heat treatment of the casting. Where
intermediate inspections have been performed, the manufacturer is to
furnish the documentation of the results upon request to the Surveyor.
3.2 Surface Condition
3.2.1 Castings are to be examined in the final delivery condition free from
any extraneous materials such as scale, dirt, grease or paint that may
affect the efficacy of the testing being performed. A thin coating of
contrast paint is permissible when using magnetic particle techniques.
3.2.2 Unless otherwise specified in the order, magnetic particle test is to be
carried out within 0.3 [mm] of the final machined surface condition for
AC techniques or within 0.8 [mm] for DC techniques.
Classification Notes Indian Register of Shipping
Guidelines for Non-Destructive Examination of Steel Castings for Marine Application –
January 2005
Page 4 of 17
3.2.3 Ultrasonic testing is to be carried out after the castings have been
ground, machined or shot blasted to a suitable condition. The surfaces
of castings to be examined is to be such that adequate coupling can be
established between the probe and the casting and that excessive
wear of the probe is avoided.
4. Extent of Examination
4.1 Castings to be examined
4.1.1 Castings to be examined by NDE methods are identified in Figures 1 to
6. The list of castings is not definitive. Criteria for the examination of
other castings not indicated in these guidelines will be subject to prior
agreement.
4.2 Zones to be examined
4.2.1 Zones to be examined in nominated castings are identified in Figures 1
to 6. Examinations are to be made in accordance with an approved
inspection plan. The plan is to specify the extent of the examination,
the examination procedure, the quality level or, where necessary,
quality level for different locations of the castings.
4.2.2 In addition to the areas identified in Figures 1 to 6, surface inspections
are to be carried out in the following locations:
- at all accessible fillets and changes of section,
- in way of fabrication weld preparation, for a band width of 30 [mm],
- in way of chaplets,
- in way of weld repairs,
- at positions where surplus metal has been removed by flame
cutting, scarifying or arc-air-gouging.
4.2.3 Ultrasonic testing is to be carried out in the zones indicated in Figures
1 to 6 and also at the following locations:
- in way of all accessible fillets and at pronounced changes of
section,
- in way of fabrication weld preparations for a distance of 50 [mm]
from the edge,
- in way of weld repairs where the original defect was detected by
ultrasonic testing,
- in way of riser positions,
- in way of machined areas particularly those subject to further
machining such as bolt hole positions.
Classification Notes Indian Register of Shipping
Guidelines for Non-Destructive Examination of Steel Castings for Marine Application –
January 2005
Page 5 of 17
In the case of castings such as rudder horns, which may have a large
surface area still untested after the above inspections have been
applied, an additional ultrasonic inspection of the untested areas are to
be made along continuous perpendicular grid lines on nominal 225
[mm] centres, scanning from one surface only.
5. Examination Procedures
5.1 Visual Inspection
5.1.1 Steel castings which are required to undergo NDE are to be subjected
to 100% visual examination of all surfaces to ensure that the surface is
suitable for the proposed NDT. Unless otherwise agreed, the visual
and surface crack detection inspections are to be carried out in the
presence of the Surveyor.
5.2 Surface Crack Detection
5.2.1 The testing procedures, apparatus and conditions of magnetic particle
testing and liquid penetrant testing are to comply with recognized
national or international standards. Magnetic particle inspection will be
carried out in preference to liquid penetrant testing except in the
following cases:
- austenitic stainless steels,
- interpretation of open visual or magnetic particle indications,
- at the instruction of the Surveyor.
5.2.2 For magnetic particle testing attention is to be paid to the contact
between the casting and the clamping devices or stationary
magnetization benches in order to avoid local overheating or burning
damage in its surface. Prods are not to be permitted on finished
machined items. Note that the use of solid copper at the prod tips must
be avoided due to the risk of copper penetration.
5.2.3 When indications have been detected as a result of the surface
inspection, acceptance or rejection is to be decided in accordance with
Section 6.
5.3 Volumetric Inspection
5.3.1 Volumetric inspection in accordance with these guidelines is to be
carried out by ultrasonic testing using the contact method with straight
beam and/or angle beam technique. The testing procedures, apparatus
and conditions of ultrasonic testing are to comply with the recognized
national or international standards. Radiographic testing may be
carried out on the basis of prior agreement with IRS.
Classification Notes Indian Register of Shipping
Guidelines for Non-Destructive Examination of Steel Castings for Marine Application –
January 2005
Page 6 of 17
5.3.2 Unless otherwise considered necessary, only those areas shown in the
agreed inspection plan need to be tested.
5.3.3 Ultrasonic scans are to be made using a 0 probe of 1 – 4 MHz (usually
2MHz) frequency. Whenever possible scanning is to be performed from
both surfaces of the casting and from surfaces perpendicular to each
other. Lower frequency probes are recommended in order to increase
signal to noise ratio.
5.3.4 The back wall echo obtained on parallel sections to be used to monitor
variations in probe coupling and material attenuation. Any reduction in
the amplitude of the back wall echo without evidence of intervening
defects is to be corrected. Attenuation in excess of 30 dB/m could be
indicative of an unsatisfactory annealing heat treatment.
5.3.5 Machined surfaces, especially those in the vicinity of riser locations and
in the bores of stern boss castings, is also to be subject to a near
surface (25 mm) scan using a twin crystal 0 probe. Additional scans
on machined surfaces are of particular importance in cases where
boltholes are to be drilled or where surplus material such as ‘padding’
has been removed by machining thus moving the scanning surface
closer to possible areas of shrinkage. Also, it is advisable to examine
the machined bores of castings using circumferential scans with 70
probes in order that axial radial planar flaws such as hot tears can be
detected. Fillet radii should be examined using 45, 60 or 70 probes
scanning from the surfaces / direction likely to give the best reflection.
5.3.6 In the examinations of those zones nominated for ultrasonic
examination the reference sensitivity is to be established against a 6
[mm] diameter disk reflector. Sensitivity can be calibrated either against
6 [mm] diameter flat bottomed hole(s) in a reference block (or series of
blocks) corresponding to the thickness of the casting provided that a
transfer correction is made, or, as a preferred alternative, by using the
DGS (distance-gain-size) method. The DGS diagrams issued by a
probe manufacturer identify the difference in dB between the amplitude
of a back wall echo and that expected from a 6 [mm] diameter disk
reflector. By adding this difference to the sensitivity level initially set by
adjusting a back wall echo to a reference height e.g. 80%, the
amended reference level will be representative of a 6 [mm] diameter
disk reflector. Similar calculations can be used for evaluation purposes
to establish the difference in dB between a back wall reflector and disk
reflectors of other diameters such as 12 or 15 [mm].
5.3.7 Having made any necessary corrections for differences in attenuation
or surface condition between the reference block and the casting any
indications received from the nominated zones in the casting that
exceed the 6 [mm] reference level is to be marked for evaluation
against the criteria given in 6.3 below. Evaluation is to include
Classification Notes Indian Register of Shipping
Guidelines for Non-Destructive Examination of Steel Castings for Marine Application –
January 2005
Page 7 of 17
additional scans with angle probes in order that the full extent of the
discontinuity can be plotted.
6. Acceptance Criteria
6.1 Visual Testing
6.1.1 All castings are to be free of cracks, crack-like indications, hot tears,
cold shuts or other injurious indications. Thickness of the remains of
sprues or risers is to be within the casting dimensional tolerance.
6.1.2 Additional magnetic particle, dye penetrant or ultrasonic testing may be
required for a more detailed evaluation of surface irregularities at the
request of the Surveyor.
6.2 Surface Crack Detection
6.2.1 The following definitions relevant to indications apply:
Linear indication = an indication in which the length is at least
three times the width
Non-linear = an indication of circular or elliptical shape
indication with a length less than three times the
width
Aligned indication = three or more indications in a line,
separated by 2 [mm] or less edge-to-edge
Open indication = an indication visible after removal of the
magnetic particles or that can be detected
by the use of contrast dye penetrant
Non-open = an indication that is not visually detectable
indication after removal of the magnetic particles or
that cannot be detected by the use of
contrast dye penetrant
Relevant indication = an indication that is caused by a condition
or type of discontinuity that requires
evaluation.
Only the indications which have any
dimension greater than 1.5 [mm] are to be
considered relevant.
Classification Notes Indian Register of Shipping
Guidelines for Non-Destructive Examination of Steel Castings for Marine Application –
January 2005
Page 8 of 17
6.2.2 For the purpose of evaluating indications, the surface is to be divided
into reference band length of 150 [mm] for level MT1/PT1 and into
reference areas of 22500 [mm2] for level MT2/PT2. The band length
and/or areas are to be taken in the most unfavourable locations relative
to the indications being evaluated.
6.2.3 The following quality levels recommended for magnetic particle testing
(MT) and/or liquid penetrant testing (PT) area:
Level MT1/PT1 – fabrication weld preparation and weld repairs.
Level MT2/PT2 – other locations nominated for surface crack detection
in Figures 1 to 6.
The allowable numbers and sizes of indications in the reference band
length and/or area are given in Table 1. The required quality level is to
be shown on the manufacturer’s inspection plan. Cracks and hot tears
are not acceptable.
Table 1 : Allowable number and size of indications in a reference
band length / area
Quality Max. number Type of Max. Max.
Level of indications indication number for dimension of
each type single
indication,
[mm]2)
MT1/PT1 4 in 150 mm Non-linear 4 1) 5
length Linear 4 1) 3
Aligned 4 1) 3
MT2/PT2 20 in 22500 Non-linear 10 7
[mm2] area Linear 6 5
Aligned 6 5
Notes :
1) 30 [mm] min. between relevant indications.
2) In weld repairs, the maximum dimension is 2 [mm].
6.3 Volumetric Testing
6.3.1 Acceptance criteria for ultrasonic testing are identified in Table 2 as
UT1 and UT2. As stated in 4.2.1 the quality levels applicable to the
zones to be examined are to be identified on an inspection plan. The
following quality levels are nominated for the castings identified in
Figures 1 to 6.
Classification Notes Indian Register of Shipping
Guidelines for Non-Destructive Examination of Steel Castings for Marine Application –
January 2005
Page 9 of 17
Level UT1 is applicable to:
- fabrication weld preparations for a distance of 50 [mm].
- 50 [mm] depth from the final machined surface including boltholes.
- Fillet radii to a depth of 50 [mm] and within distance of 50 [mm] from
the radius end.
- Castings subject to cyclic bending stresses e.g. rudder horn, rudder
castings and rudder stocks – the outer one third of thickness in the
zones nominated for volumetric examination by Figures 1 to 6.
- discontinuities within the examined zones interpreted to be cracks
or hot tears.
Level UT2 is applicable to:
- other locations nominated for ultrasonic testing in Figures 1 to 6 or
on the inspection plan.
- positions outside locations nominated for level UT1 examination
where feeders and gates have been removed.
- Castings subject to cyclic bending stresses – at the central one third
of thickness in the zones nominated for volumetric inspection by
Figures 1 to 6.
6.3.2 Ultrasonic acceptance criteria for other casting areas not nominated in
Figures 1 to 6 will be subject to special consideration based on the
anticipated stress levels and the type, size and position of the
discontinuity.
Table 2 : Ultrasonic acceptance criteria for steel castings
Quality Allowable disc Max. number of Allowable
Level shape indications to be length of linear
according to registered 2) indications
DGS 1) [mm] [mm] 3)
UT1 >6 0 0
UT2 12 – 15 5 50
> 15 0 0
Notes:
1) DGS : distance-gain-size
2) Grouped in an area measuring 300 x 300 [mm]
3) Measured on the scanning surface.
Classification Notes Indian Register of Shipping
Guidelines for Non-Destructive Examination of Steel Castings for Marine Application –
January 2005
Page 10 of 17
7. Reporting
7.1 General
All reports of non-destructive examinations to include the following
items:
1) Date of testing
2) Names and qualification level of inspection personnel
3) Type of casting
4) Product number for identification
5) Grade of steel
6) Heat treatment
7) Stage of testing
8) Locations for testing
9) Surface condition
10) Test standards used
11) Calibration sensitivity
12) Results
13) Statement of acceptance / non-acceptance
14) Locations of reportable indications
15) Details of weld repairs including sketches.
7.2 In addition to the items listed in 7.1, reports of surface crack detection
inspections are to include at least the following items:
- for liquid penetrant testing; the consumables used,
- for magnetic particle testing: method of magnetizing, test media and
magnetic field strength.
7.3 In addition to the items listed in 7.1, reports of ultrasonic inspection
should include at least the following items:
- flaw detector, probes, calibration blocks and couplant used.
8. Rectification of Defects
8.1 Defects and unacceptable indications must be repaired as
indicated below:
8.1.1 Defective parts of material may be removed by grinding or by chipping
and grinding or by arc air-gouging. Thermal methods of metal removal
should only be allowed before the final heat treatment. All grooves to
have a bottom radius of approximately three times the groove depth
and should be smoothly blended to the surface area with a finish equal
to that of the adjacent surface.
Classification Notes Indian Register of Shipping
Guidelines for Non-Destructive Examination of Steel Castings for Marine Application –
January 2005
Page 11 of 17
8.1.2 Weld repairs should be suitably classified. Major repairs are those:
- where the depth is greater than 25% of the wall thickness or 25
[mm] whichever is less,
- where the total weld area on a casting exceeds 2% of the casting
surface noting that where a distance between two welds is less than
their average width, they are to be considered as one weld.
Major repairs require the approval of IRS before the repair is carried
out. The repair is to be carried out before final furnace heat treatment.
8.1.3 Minor repairs are those:
- where the total weld area (length x width) exceeds 500 [mm 2].
Minor repairs do not usually require the approval of IRS but to be
recorded on a weld repair sketch as a part of the manufacturing
procedure documents. These repairs should be carried out before final
furnace heat treatment.
8.1.4 Cosmetic repairs are:
- all other welds.
Cosmetic repairs do not require the approval of IRS but to be recorded
on a weld repair sketch. These repairs may be carried out after final
furnace heat treatment but are subject t a local stress relief heat
treatment.
8.1.5 Castings in carbon or carbon manganese steel may require pre-heating
prior to welding and also a post weld stress relieving heat treatment
depending upon their chemical composition and the dimensions and
position of the weld repairs. Post weld heat treatment to be carried out
at a temperature of not less than 550C.
8.1.6 Castings subject to the removal of defects may be supplied without
welding under the specific conditions:
- on un-machined surfaces where the depth of defect removal is not
over 15 [mm] or 10% of wall thickness, whichever is less and the
length of the removed part is not over 100 [mm].
8.1.7 Parts which are repaired should be examined by the same method as
at initial inspection as well as by additional methods as recommended
by the Surveyor.
Classification Notes Indian Register of Shipping
Guidelines for Non-Destructive Examination of Steel Castings for Marine Application –
January 2005
Page 12 of 17
N o te s : L o c a t io n o f n o n - d e s t r u c t iv e e x a m in a t io n
1) A ll s u r f a c e s : V is u a l e x a m in a t io n
2) L o c a t io n in d ic a t e d w it h ( O O O ) : M a g n e t ic p a r t ic le a n d
U lt r a s o n ic t e s t in g
3) T h e d e t a ile d e x t e n t s o f e x a m in a t io n s a n d q u a lit y le v e ls a r e
g iv e n in S e c t io n 4 a n d 6 .
F ig .1 : S t e r n F r a m e
Classification Notes Indian Register of Shipping
Guidelines for Non-Destructive Examination of Steel Castings for Marine Application –
January 2005
Page 13 of 17
B B
A -A B -B
N o te s : L o c a t io n o f n o n - d e s t r u c t iv e e x a m in a t io n
1) A ll s u r f a c e s : V is u a l e x a m in a t io n
M a g n e t ic p a r t ic le a n d U lt r a s o n ic t e s t in g .
2) T h e d e t a ile d e x t e n t s o f e x a m in a t io n s a n d q u a lit y le v e ls a r e
g iv e n in S e c t io n 4 a n d 6 .
F ig .2 : R u d d e r s t o c k
Classification Notes Indian Register of Shipping
Guidelines for Non-Destructive Examination of Steel Castings for Marine Application –
January 2005
Page 14 of 17
B B
A -A B -B
N o te s : L o c a t io n o f n o n - d e s t r u c t iv e e x a m in a t io n
1) A ll s u r f a c e s : V is u a l e x a m in a t io n
M a g n e t ic p a r t ic le a n d U lt r a s o n ic t e s t in g .
2) T h e d e t a ile d e x t e n t s o f e x a m in a t io n s a n d q u a lit y le v e ls a r e
g iv e n in S e c t io n 4 a n d 6 .
F ig .2 : R u d d e r s t o c k
N o te s : L o c a t io n o f n o n - d e s t r u c t iv e e x a m in a t io n
1) A ll s u r f a c e s : V is u a l e x a m in a t io n
2) L o c a t io n in d ic a t e d w it h ( O O O ) : M a g n e t ic p a r t ic le a n d
U lt r a s o n ic t e s t in g
3) L o c a t io n in d ic a t e d w it h ( ) : U lt r a s o n ic t e s t in g
4) T h e d e t a ile d e x t e n t s o f e x a m in a t io n s a n d q u a lit y le v e ls a r e
g iv e n in S e c t io n 4 a n d 6 .
F ig .3 : S t e r n B o s s
Classification Notes Indian Register of Shipping
Guidelines for Non-Destructive Examination of Steel Castings for Marine Application –
January 2005
Page 15 of 17
N o te s : L o c a t io n o f n o n - d e s t r u c t iv e e x a m in a t io n
1) A ll s u r f a c e s : V is u a l e x a m in a t io n
2) L o c a t io n in d ic a t e d w it h ( O O O ) : M a g n e t ic p a r t ic le a n d
U lt r a s o n ic t e s t in g
3) L o c a t io n in d ic a t e d w it h ( ) : U lt r a s o n ic t e s t in g
4) T h e d e t a ile d e x t e n t s o f e x a m in a t io n s a n d q u a lit y le v e ls a r e
g iv e n in S e c t io n 4 a n d 6 .
F ig . 4 : R u d d e r H o r n
Classification Notes Indian Register of Shipping
Guidelines for Non-Destructive Examination of Steel Castings for Marine Application –
January 2005
Page 16 of 17
N o te s : L o c a t io n o f n o n - d e s t r u c t iv e e x a m in a t io n
1) A ll s u r f a c e s : V is u a l e x a m in a t io n
2) L o c a t io n in d ic a t e d w it h ( O O O ) : M a g n e t ic p a r t ic le a n d
U lt r a s o n ic t e s t in g
3) L o c a t io n in d ic a t e d w it h ( ) : U lt r a s o n ic t e s t in g
4) T h e d e t a ile d e x t e n t s o f e x a m in a t io n s a n d q u a lit y le v e ls a r e
g iv e n in S e c t io n 4 a n d 6 .
F ig . 5 : R u d d e r ( U p p e r P a r t )
Classification Notes Indian Register of Shipping
Guidelines for Non-Destructive Examination of Steel Castings for Marine Application –
January 2005
Page 17 of 17
N o te s : L o c a t io n o f n o n - d e s t r u c t iv e e x a m in a t io n
1) A ll s u r f a c e s : V is u a l e x a m in a t io n
2) L o c a t io n in d ic a t e d w it h ( O O O ) : M a g n e t ic p a r t ic le a n d
U lt r a s o n ic t e s t in g
3) L o c a t io n in d ic a t e d w it h ( ) : U lt r a s o n ic t e s t in g
4) T h e d e t a ile d e x t e n t s o f e x a m in a t io n s a n d q u a lit y le v e ls a r e
g iv e n in S e c t io n 4 a n d 6 .
N o te s : L o c a t io n o f n o n - d e s t r u c t iv e e x a m in a t io n
1) AFllig
s u. r5f a :c eRsu: d d e r ( U p p e r P a r t ) V is u a l e x a m in a t io n
2) L o c a t io n in d ic a t e d w it h ( O O O ) : M a g n e t ic p a r t ic le a n d
U lt r a s o n ic t e s t in g
3) L o c a t io n in d ic a t e d w it h ( ) : U lt r a s o n ic t e s t in g
4) T h e d e t a ile d e x t e n t s o f e x a m in a t io n s a n d q u a lit y le v e ls a r e
g iv e n in S e c t io n 4 a n d 6 .
F ig . 6 : R u d d e r ( L o w e r P a r t )
Classification Notes Indian Register of Shipping
