TM
INTERFLOW
INTERFLOW FIG.2001 / FIG.2008 PENSTOCKS
DESIGN FEATURES
1. True Bi-directional operation with no “on/off” seat pressure differential
restrictions that allows for positive shut-off in either direction
2. Compression sealing for more efficient sealing using synthetic rubber
3. Compression sealing eliminates grit and fines seat wear common in metal seated
cast iron penstocks
4. Low friction operation using HDPE guides to take up lateral load.
5. Light weight, simple installation
6. Unlimited custom built options for unequal width & height requirements,
including materials composition
7. Standard flush bottom design eliminates debris build-up
8. Reduced operating torque
INTERFLOW FIG.2018 ATTRIBUTES
Interflow Fig.2018 Penstock being compression sealed are not affected by “ON” or
“OFF” seating forces.
Flat back mounting using chemical anchors & expanding grout proper setting up off the
leveling nuts on the mounting bolts eliminates frame twist.
Where the operating mechanism is located remote from the unit, further consideration
will need to be given to a floor stand & a headstock to support the floor stand.
304/316 stainless steel angle, channel sections or a mixture, light weight, and reinforced
with fillets if necessary.
304/316 plate is ribbed if necessary to meet pressure requirements.
Polyurethane, NBR, EPDM or hypalon mould on extrusion reinforced with stainless steel
wire (optional). One piece sealing on both edges & bottom of the gate.
PENSTOCK SPECIFICATION
GENERAL
Each penstock shall be of the flush invert, rising stem design.
All penstocks shall have frames and gates of 304/316 stainless steel construction. All
assembly Bolts, Nuts and Washers shall be 304/316.
All components of the penstocks and actuators shall be designed that no parts thereof will
be stressed beyond their safe working limits.
FRAMES
Frames shall be of rigid construction to resist all loads reasonably expected to be
encountered in service for the life of the penstocks. Frames shall be suitably reinforced
and provided with corner and/or side gussets where necessary.
Wall-mounted penstocks shall have frames suitable for bolting direct to concrete
structures. Sealing between the frames and concrete structures will be achieved by
grouting. Channel-mounted penstocks will be cast into rebates in the concrete walls.
Frames shall provide a guide rail along which the gate slides to fully open and close
unobstructed and shall be of a length sufficient to support at least one-half of the gate in
the fully opened position. Design of the guide rail shall be such that it is self-cleaning and
that clogging is minimal.
For wall mounted penstocks the bolts securing the penstocks to the wall shall not impose
any loads on the gate.
Flush bottom closure design shall incorporate a resilient seal securely contained at the
invert of the frame to preclude loosening in service. The seal shall provide a flat plane
across the bottom of the gate without projections into the opening to obstruct flow.
Stainless steel gates shall be made up of a single piece except for larger sizes where a two
(2) piece composition is required, whereby the gates will be joined by means of welding.
Gates will be adequately ribbed when necessary to resist in-service loads. Sliding
surfaces that come into contact with the seat facings shall be accurately machined.
The gate shall be of sufficient strength to withstand the maximum unbalanced head
without deflection or distortion that would affect the operation of the penstock or reduce
the water tightness.
Stems shall be of ample cross section to prevent buckling or permanent distortion under
all operating conditions. The threads of the stem shall be machined out ACME type, ¼
pitch, single start, and anti-clockwise closing. Rising stems shall be provided with stops
to prevent over-travel of the gate in either direction.
Drive nuts shall be machined from gunmetal (LG2) or bronze unless otherwise specified.
On rising stem penstocks, the drive nut shall be threaded and keyed or threaded and
pinned to the stem. On non-rising stem penstocks, the drive nut shall be threaded but not
keyed or pinned to the stem so that the nut gate can move up the stem as the stem turns.
SEALING
Frames shall be fitted with moulded, synthetic rubber, EPDM (70A durometer) or double
density polyurethane seats with wire reinforcing (optional).
Seats shall be in one piece and provide continuous contact with the gate along the bottom
and sides of the frame.
Seats shall be held in position by High-density polyethylene (HDPE) retainers
attached to the gate guides at bottom of the frame, with stainless steel bolts and nuts.
Retainers shall be fitted to both sides of the moulded seat sections. Retainers fitted to the
gate guides shall be machined to a smooth surface and positioned to minimize transverse
gate movement and provide a low friction surface to carry gate loads.
The seats shall be trimmed back to the thickness of the gate so that contact between the
packing and the gate/seat interface is uninterrupted.
HAND WHEEL
Hand wheels may be fabricated or cast in mild steel, stainless steel or cast iron. Castings
shall be free from laminations and fins.
EXTENSION SPINDLES
Extension spindles and wall brackets shall be fabricated from stainless steel type 304.
Spindle tubes shall be of sufficient interval diameter to provide adequate stem clearance.
When tubes are joined, welds shall be ground smooth and polished.
Wall brackets shall have HDPE stem guides to suit the extension spindle. The brackets
spacing shall be varies due to spindle size (Diameter).
PEDESTALS / HEADSTOCKS
Where pedestals, commonly known as headstocks are required, they shall be suitable for
bolting onto concrete floors and shall rigidly support the actuator or hand wheel. Each
pedestal shall be of such height that the horizontal axis of the hand wheel, both in the
case of hand wheel operated penstocks and actuated penstocks is approximately 900mm
above the operating level, which corresponds to the base of the pedestal.
AVAILABLE PEDESTAL / HEADSTOCK CONFIGURATION
Manual Gearbox Actuator Pneumatic Indicator Cast Iron
Our series of Interflow Penstocks are made to accommodate a variety of headstocks with
different operator types, ranging from our standard manual operators using hand wheel to
gearbox, electric actuator, pneumatic actuator, and custom made bare shaft headstocks
complete with optional level indicator. The headstock base plate (mounting plate) is
machined to fit all ISO flange standards, and also custom fit sizes based on customer
requirements.
As default, these headstocks are fabricated from mild steel but are also available in mild
steel epoxy coating, galvanized mild steel, stainless steel, and cast iron upon request.
Please refer to the table below for the available options:
Description / Material Type
Flange Type Mild Steel SS304 / SS316 Cast Iron Galvanized
Manual
F-10
F-14
F-16
F-25
Others
FLOORSTAND
In the event where the site structural works does not
provide for headstock installation, a floorstand
(headstock mounting bracket) can be used to
provide support the headstock. Our standard
floorstands are fabricated using mild steel, complete
with standard black paint finishing.
Mild Steel Floorstand
PENSTOCK LEAKAGE RATES
The performance requirements of the penstocks are acceptable under BS 7775:2005,
Clause 5.2 “Penstock Leakage Rate” at 1.25 liters per minute per meter sealing surface
for on-seat operation and 2.50 liters per minute for off-seat operation.
INSTALLATION INSTRUCTIONS
1. Wall mounted Penstocks may be fixed to the wall face using “cast in” anchor
bolts or inserts. Bolts are to be sufficient in length (recommended at 170mm) to
allow for full projection through the frame with nuts and washers on the outer
frame face. See Figure 1 below:
M12 x 170mm Stud
Figure 1: M12 Stainless Steel Stud
2. Ensure the frame is square and plumb to the vertical
3. Ensure the frame is straight and not twisted. Distortion induced by bolting the
frame into a twisted position may cause seat failure.
4. When extension spindles are required it is essential that any guide brackets be
accurately aligned both plumb and square to the Penstock centerline.
5. It is essential that the floorstand and extension spindle are both square and plumb
with Penstock frame. Out of square/plumb mounting will cause excessive wear on
the actuator drive mechanism and unacceptable loads on the Penstock frame.
6. Mounting surface for the Penstock frame should be smooth, without twist. They
mush be plumb (Refer to Appendix A). If it is not, the alternative is:
a. The mounting surface should have a cement mortar screed bed applied. Bed
should be the full width of the frame channel section plus 50mm. Care should
be taken to avoid mortar build-up around mounting bolts or anchors.
b. The Penstock frame may be shimmed off the wall and lightly bolted. The
space between Penstock frame and the wall may be packed with an expanding
mortar grout.
NOTE: Take care that the grout does not extrude into the space behind the
follower, this space MUST be kept clear of grout to allow the follower bolts to be
adjusted.
7. Mounting surfaces for the headstock should be treated in the same manner as the
Penstock’s frame in step 6 above i.e. cement mortar screed bed or expanding
grout.
OPERATING INSTRUCTIONS
Penstock operation should only commence with the following points adhered to.
1. Packing box surface of Penstock should be free from sand grains, mortar, grout
and other forms of foreign matters to avoid rapid damage to seals.
2. If painting works are carried out at site, make sure that the paint (especially epoxy
paint) is not left to flow into the packing box surface as this will damage the seals.
3. Inspect and ensure back of Penstock gate is free from mortar, grout, mud etc. In
no circumstance should the stainless steel gates be painted on. If any stains are
found on the back portion of the gate, they should be first removed to make
certain a smooth surface for operation.
4. Threaded portion of shaft should be lubricated at all times with grease. Apply
sparingly to ensure even distribution of grease on the threaded shaft.
5. For manually operated Penstocks, ensure the self-lubricating Vesconite rings are
properly positioned around the drive bush to reduce friction and noise during
operation. (Refer to Appendix B)
6. The Penstock gate pressure pad bolts should only be gradually tightened if leaking
is visible at the packing box surface. Once the desired condition is met, tighten the
nut to hold the jam nut in place. See Figure 2 below:
Figure 2: Pressure Pad for tightening gate
IMPORTANT: It is essential that the Pressure Pad bolts are not over tightened.
Over tightening places unnecessary stress on the Top Seal and
undue effort on the operating mechanism that result in faster wear
and tear.
MAINTENANCE INSTRUCTIONS
Regular scheduled inspection to be made at least every 90 days. The following points
should be examined.
1. Stem Threads and drive nut, for lack of lubrication. Check thrust washer and
grease seat.
2. Ensure Penstock gate jam nut is still in place and tighten or loosen if necessary.
3. If possible, open and close the Penstock every 90 days, this ensures it is
functioning properly, and avoids adhesive of stainless steel blade to urethane seat.
4. Ensure that there is no build up of sand grains or objects at the Penstock gate
packing surface to protect the seals from being damaged. These foreign matters
should be flushed out for optimal lifespan of seals.
SPARE PARTS
• 1 set of packing seals
• 1 length of urethane seat
When ordering replacement parts for an Interflow Penstock please indicate the valve size
and the valve number. The valve serial number is stamped on the edge of the top right
portion of the Penstock frame. Alternatively, it can also be found on the marking plate
mounted to the top left portion of the Penstock frame (if available).
RESILIENT SEAT REPLACEMENT
TOOLS AND MATERIALS REQUIRED:
1.) Screw driver
2.) Swab or rag
3.) Knife
4.) Hacksaw or wire cutter
5.) Packing
6.) New seat
TO DISMANTLE:
1.) Open Penstock completely
2.) Disconnect blade clevis
3.) Remove thread shaft
4.) Remove packing gland
5.) Remove Penstock gate by swinging gate out at the top
6.) Remove HDPE seat guides
7.) Remove old packing and seat
8.) Clean out seat retaining groove
INSTALLING A NEW SEAT
Seat is a urethane section with/without a wire core (identical to old seat). By default, wire
core is not included with the seat. If required, the wire core can be placed into the seat to
ease the new seat installation process.
1.) Bend new seat material to “U” shape (only possible with wire core). Else
proceed to place the seat firmly into position.
2.) Trim one end as old seat. Take care not to stretch or elongate seat
material. Start top left, and push seat firmly into corner then the other
corner trim as previous.
3.) When seat is firmly in place reposition HDPE seat guides and
remount them accordingly.
4.) Insert gate, forcing it to completely closed position.
5.) Install packing on both sides of the gate, one row at a time. Cut packing
10- 20mm longer than length of the stuffing box or bolting hole (only
applicable for Figure 2008 model upwards). Packing must be forced into
the slightly narrower portion of box on each end between seat and side of
packing box. Alternatively a slight portion of the seat may be removed
(cut off). Be careful not to cut off in excess of what is required to prevent
any leaks from occurring.
6.) Reassemble packing gland and threaded shaft, then reconnect the clevis.
IMPORTANT:
Do not take up packing gland bolts any further than necessary to stop
packing gland leaks.
Special attention should be taken to these instructions to ensure proper seal and long seat
life.
APPENDIX A
INSTALLATION PROCEDURES
Back Nut Location
1.) Set all anchor
2.) Adjust back nut so that:
i. Grout thickness is at minimum
15mm
ii. Nuts are in line and plumb
iii. Nuts are in wind so there will be
no twist in the Penstock Frame
Frame Installation
1.) Set frame on back of nuts. Bolts firmly
in position
2.) Form up for and pour grout
Channel Frame Fixing Angle Frame Fixing
COMPARISON OF STRENGTH CHARACTERISTICS OF
PENSTOCK FABRICATION MATERIALS
Design
Elastic
U.T.S Corrosion Density Safety Dead
Material E'(Mpa) Limit
(Tension) Resistance (kg/M3) Factor Live Load
(Tension)
Load
Stainless Steel - 304 193 205 515 10 7850 8 13
Stainless Steel - 316 193 205 515 10 7870 8 13
Aluminium - Marine 72 83 125 8 2700 N/A N/A
Grade
Carbos Steel 200 280 420 5 7800 8 13
Cast Iron 97 43 140 3 7200 6 10
Radio of SS over CI 2.01 5.82 3.00 3.33 1.33 1.33
The above figures are intended to offer comparisons only. For design purposes, actual
conditions would need to be established.
Stainless Steel offers advantages in design flexibility, corrosion resistance and long term
maintenance. Although the corrosion resistance of Cast Iron can be improved by the use
of epoxy or similar surface treatments, mechanical, damage can occur which will lead to
water penetration beneath the treated surface with resultant “blistering” of the treated
surface.
The significantly superior qualities of Stainless Steel Young’s Modulus (E), Elastic
Limit, and Ultimate Tensile Strength (U.T.S) will result in a far lighter penstock. Size for
size, this can offer a Stainless Steel unit which can vary from 20% - 60% lighter than the
Cast Iron equivalent.
Cost comparisons are difficult as fabricated Stainless Steel penstocks are designed to a
maximum condition as it is not practical to vary patterns and cast to specific conditions.
As a very broad indication, Cast Iron penstocks may have a cost advantage over Stainless
Steel in size up to 0.02 square meter in opening size. From that point on it is likely
Stainless Steel will offer cost advantages as light weight, corrosion and maintenance
attractions.
The stainless alloy resists most oxidizing acids and can withstand all ordinary rusting.
HOWEVER, IT WILL TARNISH. It is immune to foodstuffs, sterilizing solutions, most
of the organic chemicals and dyestuffs, and a wide variety of inorganic chemicals. Type
304, or one of its modifications, is the material specified more than 50% of the time
whenever a stainless steel is used.
Type 304 is also used for the dye tanks, pipelines buckets, dippers, etc. that come in
contact with the lormic, acetic, and other organic acids used in the dyeing industry. In the
marine environment, because of it slightly higher strength and wear resistance than type
316 it is also used for nuts, bolts, screws, and other fasteners. It is also used for springs,
cogs, and other components where both wear and corrosion resistance is needed.
Type Analysis of Stainless Type 304:
Carbon 0.08% max. Silicon 1.00% max.
Manganese 2.00% max. Chromium 18.00-20.00%
Phosphorus 0.045% max. Nickel 8.00-10.50%
Sulfur 0.030% max.
For severe environments, there are many industrial processes that require a higher level
of resistance to corrosion than Type 304 can offer. For these applications, Type 316 is
the answer.
Type 316 is also austenitic, non-magnetic, and thermally The main component
nonhardenable stainless steel like Type 304. The carbon
that differentiates 316
content is held to 0.08% maximum, while the nickel
content is increased slightly. What distinguishes Type 316 from 304 is the addition
from Type 304 is the addition of molybdenum up to a of molybdenum
maximum of 3%.
Molybdenum increases the corrosion resistance of this chromium-nickel alloy to
withstand attack by many industrial chemicals and solvents, and, in particular, inhibits
pitting caused by chlorides. As such, molybdenum is one of the single most useful
alloying additives in the fight against corrosion.
By virtue of the molybdenum addition, Type 316 can withstand corrosive attack by
sodium and calcium brines, hypochlorite solutions, phosphoric acid; and the sulfite
liquors and sulfurous acids used in the paper pulp industry. This alloy, therefore, is
specified for industrial equipment that handles the corrosive process chemicals used to
produce inks, rayons, photographic chemicals, paper, textiles, bleaches, and rubber.
Type 316 is the main stainless used in the marine environment, with the exception of
fasteners and other items where strength and wear resistance are needed, then Type 304
(18-8) is typically used.
Type Analysis of Stainless Type 316:
Carbon 0.08% max. Silicon 1.00% max.
Manganese 2.00% max. Chromium 16.00-18.00%
Phosphorus 0.045% max. Nickel 10.00-14.00%
Sulfur 0.030% max. Molybdenum 2.00-3.00%
There are many issues involved in the question of the advantages and disadvantages of
304 and 316 components. 316 stainless has 2% to 2.5% molybdenum compared to 304,
which has about 0.5%. 316 has slightly more nickel and slightly less chromium than 304.
The result of these slight differences in chemical composition is that 316 stainless steel is
substantially more resistant to corrosion.
In terms of machinability, weldability, particle generation and vacuum properties, there
are no real differences between 316 and 304. In all other technical respects that are of
interest to our customers, 316 and 304 are identical.
In summary, 316 stainless is more expensive than 304 due to the
316 stainless
higher Nickel and Molybdenum content and has higher corrosion
resistance, higher tensile strength, and a slightly grayer finish. For generally costs
most applications, 304 has the best combination of corrosion 25%-35% more
resistance, mechanical properties, and cost. For high corrosion than 304
resistance in food, biomedical, marine, and heat exchanger
applications, 316 can be worth the price difference. The resistance to solvents, chlorides,
acetic acid, and especially to salt water can make 316 the preferred choice.
Additional Facts:
• Molybdenum (Mo) is a refractory metallic element used principally as an alloying
agent in steel, cast iron, and superalloys to enhance hardenability, strength,
toughness, and wear and corrosion resistance.
• Nickel (Ni) is a transition element that exhibits a mixture of ferrous and
nonferrous metal properties. It is both siderophile (i.e., associates with iron) and
chalcophile (i.e., associates with sulfur).
• Chromium (Cr) use in iron, steel, and nonferrous alloys enhances hardenability
and resistance to corrosion and oxidation. The use of chromium to produce
stainless steel and nonferrous alloys are two of its more important applications.
For more detailed analysis, please refer to NiDi Technical Series Publication No.10 076,
“Stainless Steel in municipal waste water treatment plants”.
APPENDIX B
PENSTOCK ASSEMBLY (MANUAL OPERATED)
Hand Wheel
Bronze Bush
Vesconite Ring
Headstock
Stem Joint Floorstand (Optional)
Wall Bracket
Stem / Rod
Clevis
Penstock Gate
Penstock Frame
BUSH INSTALLATION AND VESCONITE POSITION
Hand Wheel
0 Brass Nut
Vesconite Ring
Bronze Bush
Vesconite Ring
Headstock
Standard Materials
No. Part Material
1 Handwheel Cast Iron
2 Drive Nut LG2 / Bronze
3 Stem / Spindle SS304 / SS316
4 Clevis SS304 / SS316
5 Gate SS304 / SS316
6 Frame SS304 / SS316
7 Guides HDPE
8 Top Guide HDPE
9 Packing EPDM
10 Guides HDPE
11 Bolt & Nut SS304 / SS316
12 Seat EPDM
PS: In line with our continuing product development, SS Marketing (M) Sdn. Bhd. Reserves the RIGHT to
change and improve the design, specifications, dimensions, etc. without prior notice
