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Join Date: Mar 2017
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Please Tell Me What Flange Thickness To Use For MS Sheet

03/22/2017 4:01 AM

We are making pressure vessels with ms for sand filters etc. could you kindly guide me on thickness of flanges to be used? If any information is needed, we shall be glad to provide them. Some additional information is given below:

Temperature: Ambient. (generally lower than ambient because the vessel contains water)

Pressure 3.5 Kgs.

Flange Dia. varies between 1/2 inches to 40 inches.

We are immediately interested for thickness for 2 inches to 8 inch dia.

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#1

Re: Please tell me what flange thickness to use for MS sheet

03/22/2017 4:08 AM

"3.5 Kgs" is not a pressure unit. Please clarify.

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#2

Re: Please tell me what flange thickness to use for MS sheet

03/22/2017 4:39 AM

You really need to explain why you are making vessels that haven't been fully designed, Mildred. You also need to explain why your burst/collapse insurance liability cover provider hasn't become involved in order to advise. What nonsense.

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#3

Re: Please tell me what flange thickness to use for MS sheet

03/22/2017 5:30 AM

Why not use a standard NP6 pipe flange?

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#5
In reply to #3

Re: Please tell me what flange thickness to use for MS sheet

03/22/2017 6:42 AM

I should have added - assuming you mean 3.5 kg/cm2. And NP6 or the lowest rating available above NP6, as NP6 is not available in 2 inch.

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#4

Re: Please tell me what flange thickness to use for MS sheet

03/22/2017 6:00 AM

Thickness or rating. Is not the Same. Rating 300# is enough.

WHAT IS THE PRESSURE RATING OF THAT

FLANGE?

What is the pressure rating of a Class of 150 flange?

What is the pressure rating of a class 250 flange? The

answer to both of those questions is the same. It

depends! This bulletin will bring to light some of the

background information concerning the actual

pressure ratings of standard flanges and how it relates

to the water works industry.

RELATED STANDARDS

Probably, the standards most often referred to

concerning flanges are from the B16 Committee of

the American Society of Mechanical Engineers. The

most common are

- ASME/ANSI B16.1-1989 “Cast Iron Pipe Flanges

and Flanged Fittings”

- ASME/ANSI B16.5-1988 “Pipe Flanges and

Flanged Fittings”

- ASME/ANSI B16.42-1987 “Ductile Iron Pipe

Flanges and Flanged Fittings”

These standards cover grey iron, ductile iron, various

steels, and nickel alloy flanges with classifications

from Class 125 to Class 2500. Some of the American

Water Works Association standards that deal with

flanges are

- ANSI/AWWA C110/A21.10-87 “American

National Standard for Ductile Iron and Gray Iron

Fittings, 3 In. Through 48 In., for Water and Other

Liquids”

- ANSI/AWWA C115/A21.15-88 “American

National Standard for Flanged Ductile-Iron Pipe

With Threaded Flanges”

- ANSI/AWWA C207-86 “Steel Pipe Flanges for

Waterworks Service-Sizes 4 In. Through 144 In.”

The primary objective of these standards, ASME and

AWWA, is to describe flanges and flange materials

in a manner that allows for compatibility with other

flanges. The “125 pound” or the “150 pound” flanges

are used most frequently. Those flange dimensions

are the same as those referenced to in AWWA C110

and AWWA C115.

BACKGROUND

The following is a condensed time line of some of the

events shaping the formation of the B16 standards

that are in use today. This information is taken from

the forewords of the standards listed previously.

1894-- A standard flange template was adopted by

ASME for low pressure applications.

1901-- A manufacturer’s standard was established for

the 250 pound flange pattern.

1914-- ASME and various manufacturers developed

a compromise standard for standard steam

pressures of 125 psi (345 degrees F) and 250

psi (400 degrees F).

1918-- Flange patterns were standardized for 50

pound steam ratings as well as 800, 1200, and

3000 pound hydraulic flanges.

1932-- The pressure ratings for the 250 lb. and 1350

lb. flanges were increased.

1936-- Pressure-Temperature ratings were

established for all flanges.

1942-- Pressure-Temperature ratings were revised.

1957-- With the introduction of ductile iron,

confusion arose over pressure-temperature

ratings relative to grey iron and steel.

1973-- The flange designations were changed from

“pound” to “Class”. The 150 pound flange

became the Class 150 flange, etc.

1975-- Higher grades of iron necessitated the

establishment of a second set of ratings for

smaller flange sizes.

1979-- B16.42 was accepted.

1981-- More materials were added to B16.5.

It can be seen from the sequence of events over the

past century that flange ratings have developed over a

period of time where materials have improved and

large amounts of data have been taken. The

standardization of the flange and flange materials has

been a long, steady process that will continue to

change as materials and techniques evolve.

PRESSURE RATINGS

The B16 standards deal with flanges made from

many different materials, that will be used to transmit

FL-01

2-94

many types of materials, at many different

temperatures. As a result the pressure ratings change

as the temperature changes. For example:

Class 150 Flange Template B16 Pressure Ratings

Spec. Material Press. Rat.

(psi)

Temp. (F)

B16.5 Var. Carbon Steels 235-

290

100

B16.5 Var. Nickel Alloys 90-290 100

B16.5 Var. Carbon Steels 140 600

B16.5 Var. Nickel Alloys 85-140 600

B16.42 Ductile Iron 250 100

B16.42 Ductile Iron 140 600

In addition to the pressure rating listed in Section 2.1

of B16.42-1987 there is an equation in Annex A that

can be used to derive the ambient pressure ratings for

Class 150 and Class 300 flanges. With a minimum

yield strength of 42,000 psi for ductile iron, the

ambient temperature pressure rating for a Class 150

flange comes out to be 331 psi. It is possible,

therefore, to get two different pressure ratings from

the same standard.

The information from the B16 standards does not

begin to address other flanging materials that are on

the market. You can obtain flanges with Class 150

templates that are made of PVC, PE and many

special non-metallic materials. And what about

copper, brass, and special alloy steels?

All of this confusing information is an indirect

answer to the two questions presented at the

beginning of this bulletin. There are many factors that

affect the rated pressure of Class 150 and Class 300

flanges. In most industrial applications, it depends on

the flange material and the operating temperature. By

the way Class 125 and Class 150 flanges have the

same flange template. In like manner, Class 250 and

Class 300 flanges have the same flange template.

APPLICATION

In the waterworks industry things are simpler because

the variable are narrowly defined. Most systems will

operate with an ambient temperature of less than 100

degrees F. and the transmitted media will generally

be water or water based. According to AWWA C110

the pressure rating for ductile iron, flanged fittings is

250 psi in all sizes. The proof test for these fittings is

a hydrostatic pressure test to three times the rated

pressure. It is interesting that, in the same standard,

mechanical joint fittings up through the twenty-four

inch size with the same wall thickness as the flanged

fittings, have a pressure rating of 350 psi with a three

to one safety factor. This indicates that there is not a

problem with the strength of the standard flanged

fitting that would inhibit its ability to withstand

extreme pressures. There are, however, limitations

with the ability of the flange to seal at high pressures.

The standard flat faced gasket with the standard

flange is very difficult to assemble and obtain a good

seal at higher pressures. There are, however, gaskets

and products on the market to overcome the sealing

difficulty.

EBAA Iron produces two products that employ

the standard Class 150 flange template. The FLEXTEND

® family and the 2100 series MEGAFLANGE®

flange adapter. These products have pressure ratings

as high as 350 psi with safety factors from three to

one to five to one. This is possible because we use 0-

ring seals at the flange face. EBAA uses a five to one

safety factor on a pressure rating of 350 psi to mean

that the device can physically withstand the forces at

1750 psi and provide a leak free seal at the same

time.

CONCLUSION

There are more factors affecting the pressure rating

of a flange than its stated class. There are differences

in material, differences in sealing methods, and

differences in operating temperatures. Since most

waterworks applications operate at ambient

temperatures, the various temperature-pressure

ratings in the B16 standards don’t apply. The

pressure ratings listed in C110 and C115 are

generally effective.

The pressure rating for the C110 fittings and C115

flanged pipe is 250 psi with a three to one safety

factor. If a product from EBAA Iron has a pressure

rating of 350 psi with a three to one safety factor, the

flange and the seal provided are included in that

rating. The fact that these have Class 150 flange

templates does not limit their performance capability

to 150 psi or even 250 psi.

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#6

Re: Please tell me what flange thickness to use for MS sheet

03/22/2017 8:51 AM

"Caveat emptor" - Anon

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#7

Re: Please Tell Me What Flange Thickness To Use For MS Sheet

03/22/2017 10:09 AM
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#8

Re: Please Tell Me What Flange Thickness To Use For MS Sheet

03/22/2017 11:09 AM

So:

  • What does the client-approved "for construction" vessel datasheet, developed by the Process Engineer, have to say (rhetorical question - NNTR)?
  • What does the Mechanical Engineer's design calculation sheet, produced in response to the above, have to say (rhetorical question - NNTR)?
  • What does the client-approved and insurance assessed "for construction" fabrication drawing, developed by the Mechanical Engineer, have to say (rhetorical question - NNTR)?
  • What does the contractually-agreed client-approved "for construction" piping standards document have to say (rhetorical question - NNTR)?

The information being requested will be found in at least one of these four documents. None of these documents can be seen from here. Until it becomes available, stop work, for the time is better spent working on fabrications where the above information is to hand instead.

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#9

Re: Please Tell Me What Flange Thickness To Use For MS Sheet

03/22/2017 2:36 PM

Please refer to the relevant pressure vessel standards. Pressure vessels are generally very dangerous if improperly designed, hence our trepidation about giving an actual answer that may well not be safe for your particular application given the limited data.

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#10

Re: Please Tell Me What Flange Thickness To Use For MS Sheet

03/22/2017 2:53 PM

By ms I take it you mean mild steel (carbon steel)? Which grade?

Is that pressure unit in Kg/m2? Kg/cm2??? Be specific, man. Are you using flanges for manways? (This is considered bad form in the USA).

Flange thickness changes with the pressure, temperature rating on the vessel stamp. You need to get up to speed on the code, and do not take another step until you know the code for "India" up and down. If making the vessels for export to another country (America), then you better follow American code. International rules and courts will admit the American codes into evidence for any lawsuits.

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#11

Re: Please Tell Me What Flange Thickness To Use For MS Sheet

03/23/2017 10:37 AM

Please tell me where the installation is going, so that I can live far away from there.

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#12
In reply to #11

Re: Please Tell Me What Flange Thickness To Use For MS Sheet

03/23/2017 10:53 AM

You always bring out the most pertinent points!

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