Please read all instructions before attempting to install flanges.

Flanges may be used when the piping system may need to be dismantled

• the installation is temporary or mobile

• transitioning between dissimilar materials that can not be cemented together

• the installation environment is not conducive to solvent cementing

Why Choose a Vinyl Flange?

Like all vinyl pipe and fittings, vinyl flanges are lightweight,

inexpensive, and easy to install. However, PVC and CPVC

have different physical properties than metals, and

therefore special care is required to ensure that your vinyl

flanges have a long, reliable service life. Installers should

study these instructions and follow them carefully in every

installation in order to ensure satisfactory performance

and enjoy the full benefits of the GF warranty.

When using a vinyl flange, ensure that the entire system

is well-supported and that the flange does not bear the

weight of a massive, unsupported system component such

as a cast iron valve. See support instructions in the GF

Technical Manual online:

http://www.gfpiping.com/downloads/engbook/engbook.pdf

Vinyl Flanges PVC

Visually inspect flanges for cracks, deformities, and solvent

cement or other obstructions on the sealing surfaces.

Gasket

A rubber gasket must be used between the flange faces

in order to ensure a good seal. For Schedule 80 flanges,

GF recommends a 0.125” thick, full-face gasket with

Shore A scale hardness of 70±5, and the bolt torque

values published below are based on this specification.

For other hardness requirements, contact GF Technical

resistance requirements of your system.

A full-face gasket should cover the entire flange-to-flange

interface without extending into the flow path.

Table 1

Gasket Dimensions

Size (in) O.D. (in, min) I.D. (in, max)

½ 3.50 0.88

¾ 3.88 1.10

1 4.25 1.38

1¼ 4.63 1.60

1½ 5.00 1.93

2 6.00 2.44

2½ 7.00 2.91

3 7.50 3.59

4 9.00 4.64

6 11.00 6.82

8 13.50 8.66

10 16.00 10.81

12 19.00 12.09

Fasteners

It is critical to avoid excessive compression stress on a

vinyl flange. Therefore, only low-friction fastener materials

should be used. Low-friction materials allow torque to be

applied easily and gradually, ensuring that the flange is

not subjected to sudden, uneven stress during installation,

which can lead to cracking.

Either the bolt or the nut, and preferably both, should be

zinc-plated to ensure minimal friction. If using stainless

steel bolt and nut, lubricant must be used to prevent high

friction and seizing. In summary, the following fastener

combinations are acceptable:

• zinc-on-zinc, with or without lube

• zinc-on-stainless-steel, with or without lube

• stainless-on-stainless, with lube only

Cadmium-plated fasteners, while becoming more

difficult to obtain due to environmental concerns, are

also acceptable with or without lubrication. Galvanized

and carbon-steel fasteners are not recommended. Use

a copper-graphite antiseize lubricant to ensure smooth

engagement and the ability to disassemble and reassemble

the system easily.

3

Bolts must be long enough that two complete threads

are exposed when the nut is tightened by hand. Using a

longer bolt does not compromise the integrity of the flange

connection, although it wastes material and may make

tightening more difficult due to interference with nearby

system components.

Table 2

Fastener Specifications

Flange

Size (in)

No. of

Bolts

Length1

(in)

Bolt Size (in)

& Type

Washer

Size (in) &

Type2

½ 4 2½ ½-UNC ½ SAE3

¾ 4 2½ ½-UNC ½ SAE

1 4 2½ ½-UNC ½ SAE

1¼ 4 3 ½-UNC ½ SAE

1½ 4 3 ½-UNC ½ SAE

2 4 3 5/8-UNC 5/8 SAE

2½ 4 3½ 5/8-UNC 5/8 SAE

3 4 3¾ 5/8-UNC 5/8 SAE

4 8 4 5/8-UNC 5/8 SAE

6 8 4¾ ¾-UNC ¾ F4364

8 8 5¼ ¾-UNC ¾ F436

10 12 6 7/8-UNC 7/8 F436

12 12 6½ 7/8-UNC 7/8 F436

1 Suggested bolt length for flange-to-flange connection with

0.125” thick gasket. Adjust bolt length as required for other

types of connections.

2 Minimum spec. Use of a stronger or thicker washer is always

acceptable as long as published torque limits are observed.

3 Also known as Type A Plain Washers, Narrow Series.

4 ASTM F436 required for larger sizes to prevent warping at high

torque.

A washer must be used under each bolt head and nut. The

purpose of the washer is to distribute pressure over a wider

area, reducing the compression stress under the bolt head

and nut. Failure to use washers voids the GF warranty.

Torque Wrench

Compared to metals, vinyls are relatively flexible and

deform slightly under stress. Therefore, not only must

bolt torque be controlled in order to avoid cracking the

flange, but continuing to tighten the bolts beyond the

recommended torque levels may actually make the seal

worse, not better.

Because bolt torque is critical to the proper function of a

vinyl flange, a current, calibrated torque wrench accurate

to within ±1 ft-lb must be used when installing vinyl flanges.

Experienced installers may be tempted to forgo the use

of a torque wrench, relying instead on “feel.” GF does not

endorse this practice. Job-site studies have shown that

experienced installers are only slightly better than new

trainees at estimating bolt torque by feel. A torque wrench

is always recommended.

Never use an impact wrench to install a vinyl flange.

Checking System Alignment

Before assembling the flange, be sure that the two parts

of the system being joined are properly aligned. GF has

developed a “pinch test” that allows the installer to assess

system alignment quickly and easily with minimal tools.

First check the gap between the flange faces by pinching

the two mating components toward each other with one

hand as shown below. If the faces can be made to touch,

then the gap between them is acceptable.

Next check the angle between the flange faces. If the faces

are completely flush when pinched together, as shown

above, then the alignment is perfect, and you may continue

installation. Otherwise, pinch the faces together so that

one side is touching, then measure the gap between the

faces on the opposite side. The gap should be no more than

1/8”.

To assess high-low misalignment, pull the flange faces

flush together. If the faces are concentric within 1/8”, then

the high-low misalignment is acceptable.

If the gap between the mating components can not be

closed by pinching them with one hand, or if the angle or

high-low misalignment between them is too large, then

4

using the bolts to force the components together will result

in excessive stress and possible failure during or after

installation. In this case, inspect the system to find the

greatest source of misalignment and refit the system with

proper alignment before bolting.

The pinch test is a good rule of thumb, but always use

common sense as well. If it seems difficult or awkward to

pull the flange faces together, then stop the installation and

either refit the system or consult your GF representative

before proceeding.

Bolt Hole Alignment

The bolt holes of a Van Stone flange will align automatically

at the bolts are inserted and tightened. No additional

adjustment is necessary.

To align the bolt holes of a fixed flange, use standard twoholing

procedure.

Placing the Gasket

Center the gasket between the flange faces, with the bolt

holes aligned with corresponding holes in the gasket. A

full-face gasket cut to the specified dimensions (see Table

1) should come just to the inner edge of the flange face near

the flow path, or overlap the edge slightly.

Inserting the Bolts

If using copper-graphite antiseize lubricant as

recommended, apply the lubricant evenly with a brush

directly to the bolt threads, and to the nut if desired. Cover

the bolt from its tip to the maximum extent to which the nut

will be threaded.

Insert bolts through washers and bolts holes as shown:

Tighten all nuts by hand. As you tighten each nut, the nuts

on the other bolts will loosen slightly. Continue to handtighten

all of the nuts until none remain loose. Now the

flange assembly will remain in place as you prepare to fully

tighten it.

Again, when hand-tightened, at least two threads beyond

the nut should be exposed in order to ensure permanent

engagement. If less than two threads are exposed,

disassemble the flange and use longer bolts.

Tightening the Bolts

Vinyl flanges require gradual, even bolt tightening.

Tightening one bolt to the maximum recommended torque

while other bolts are only hand-tight, or tightening bolts in

the wrong order, produces uneven stresses that may result

in cracking or poor sealing.

To ensure even distribution of stresses in the fully-installed

flange, tighten the bolts in a star pattern as described in

ANSI B16.5:

For the installer’s convenience, the pattern is also indicated

by numbers molded into the vinyl flange next to each bolt

hole.

The torque required on each bolt in order to achieve

the best seal with minimal mechanical stress has been

carefully studied in laboratory and field installations, and is

given in Table 3.

To ensure even distribution of stresses and a uniform seal,

tighten the bolts to the first torque value in the sequence,

using a star pattern, then repeat the star pattern while

tightening to the next torque value, and so on up to the

maximum torque value.

Vinyls, like all polymers, deform slightly under stress. A

final tightening after 24 hours is recommended, when

practical, to ensure that any bolts that have loosened due to

relaxation of the polymer are fully engaged.

If a flange leaks when pressure-tested, retighten the bolts

to the full recommended torque and retest. Do not exceed

the recommended torque before consulting an engineer or

GF representative.

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Table 3

Multiple-Pass Bolt Torque

Size (in) Torque Sequence

(ft-lb, lubed*)

Torque Sequence

(ft-lb, unlubed**)

1st 2nd 3rd 4th 1st 2nd 3rd 4th

½ 3 5 - - 5 8 - -

¾ 3 5 - - 5 8 - -

1 3 5 - - 5 8 - -

1¼ 3 5 - - 5 8 - -

1½ 3 5 - - 5 8 - -

2 5 8 - - 5 10 12 -

2½ 5 8 10 - 10 15 18 -

3 5 12 15 - 15 20 25 -

4 10 15 20 - 15 25 32 -

6 12 24 30 - 20 32 42 -

8 15 35 40 - 30 40 50 60

10 25 50 60 - 20 40 60 70

12 30 60 72 - 20 50 65 80

* Assumes the use of SS, zinc- or cadmium-plated bolt and/or nut

along with copper-graphite antiseize lubricant brushed directly onto

the bolt threads.

** Assumes the use of zinc- or cadmium-plated bolt, nut, or both.

Never use unlubricated, uncoated bolts and nuts with vinyl flanges,

as high friction and seizing lead to unpredictable torque and a high

incidence of cracking and poor sealing.

Note that the torques listed in Table 3 are for flange-toflange

connections in which the full faces of the flanges

are in contact. For other types of connections, such as

between a flange and a butterfly valve, where the full face

of the flange is not in contact with the mating component,

less torque will be required. Do not apply the maximum

listed torque to the bolts in such connections, which may

cause deformation or cracking, since the flange is not fully

supported by the mating component. Instead, start with

approximately two-thirds of the listed maximum torque and

increase as necessary to make the system leak-free after

pressure testing.

Keep Instructions Available

Provide a copy of these instructions to every installer on the

job site prior to beginning installation. Installers who have

worked primarily with metal flanges often make critical

mistakes when installing vinyl flanges. Even experienced

vinyl installers will benefit from a quick review of good

installation practices before starting a new job.

Installation Tags

Best practices include tagging each flange with

• installer’s initials

• installation date

• final torque value (e.g., “29.2-31.5”)

• confirmation of 24-hour torque check (“y” or “n”)

This information can be recorded on pre-printed stickers,

as shown below, and placed on each flange immediately

after installation.

Experience has shown that installation tags speed up

the process of resolving system leaks and product

failures, improve communication between the contractor

and distributor or manufacturer, highlight training

opportunities, and promote worker diligence.

© Georg Fischer LLC 2009 Link to original data

 http://www.us.piping.georgefischer.com/go/597C3971199943D4416FB4A34A0403B2?action=GF_DocumentDownload&doc_uuid=597C3971199943D4416FB4A34A0403B2

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