Pump 125# and 250# Flange specifications 2

[curtis2004]

Hi Everyone,
I haven't had any previous experience with dealing cast iron body pumps. Particularly how I can connect my piping to pump flanges. I was told it could be done:
a) to buy 150# ANSI flange (or 300#) cut RF off and provide flat face gasket for it;
b) to buy 150# ANSI flange (or 300#) and provide RF gasket for it that pump side will have flat face and pump side will have RF;

What is right way of making connection?

Thank you,

Curtis

 

[Pumpsonly]

The correct method is (a).
It you use method (b),the cast iron flange can crack when you tighten the botls.

 

[curtis2004]

Pumpsonly,

Thank you for your quick responce.
I also heard that some of 250# cast iron products come with RF flanges and you have only to provide 300# steel ANSI flange. Have you heard about this?

Curtis

 

[curtis2004]

I searched Internet and found out this article about flanged connections of pumps and fittings. It seems that it fully explaines all issues regarding flange ratings.
Curtis
___________________________________________________________________________________________________________________________________________________________________
What's Up With Flanges?
There’s a lot of confusion regarding pressure ratings of flanged valves for water works service. Industry standards, manufacturer’s literature and project specifications often contradict or are subject to interpretation which leads to delays, improper equipment and potential system failures.

ASME and ANSI
Most flanged valves for water works service in North America are supplied with flanges conforming to dimensional standards developed by the American Society of Mechanical Engineers (ASME) and accredited by the American National Standards Institute (ANSI). Various “committees” within ASME are charged with developing, issuing and maintaining individual standards. The ASME “B16” committees have this responsibility for valves, flanges and flanged fittings. Standardized dimensions for cast iron flanges and flanged fittings are provided in ANSI/ASME B16.1 standard, steel and stainless steel dimensions in the ANSI/ASME B16.5 standard and ductile iron in the ANSI/ASME B16.42 standard. Compliance with the applicable standardized flange and flanged fitting dimensions is voluntary but ensures uniformity so that flanged valves from one manufacturer will bolt to flanges from another.

Flange Classes
There are four common pressure “classes” within the ANSI/ASME standards listed above. Class 125 and Class 250 are “cast iron” flanges and flanged fittings while Class 150 and Class 300 are ductile iron, steel or stainless steel. Hence, ANSI/ASME B16.1 Class 125 flanges are made from cast iron, ANSI/ASME B16.5 Class 150 can be made from steel or stainless and ANSI/ASME B16.42 Class 150 is made from ductile iron.

However, the bolting pattern is the same for both Class 125 and 150 so, regardless of material, they will bolt together. This is also the case for Class 250 and 300. Cast iron flanges are usually supplied “flat faced” while ductile iron and steel are usually “raised face.” When bolting a cast iron flange to a steel or ductile iron flange, the “raised face” of the mating flange should be removed to avoid breaking the cast iron flange when tightening the bolts.

Pressure and Temperature
The ANSI/ASME standards also provide pressure ratings for various “classes” of flanges and flanged fittings. The pressure ratings change based on the material from which it is made and/or the temperature at which it operates. The nominal flange “Class” (e.g., Class 125) generally represents the maximum working pressure at the temperature of saturated steam at that pressure. For example, an ANSI/ASME B16.1 Class 125 flange is rated for 125 PSI at 353º F.

But when used at colder temperatures, such as that of water, the ANSI/ASME maximum working pressure is higher than the nominal class. ANSI/ASME B16.1 rates Class 125 flanges and flanged fittings made from high strength cast iron for 200 PSI at temperatures up to 150º F. ANSI/ASME B16.42 rates Class 150 ductile iron flanges and fittings for 250 PSI at temperatures up to 100º F.

Complete flange and flanged fitting pressure-temperature ratings can be found in tables within the applicable ANSI/ASME B16.x standard.

Are you confused?

It gets worse.

Enter AWWA
The American Water Works Association (AWWA) also has committees charged with addressing the particular needs of the water works industry.

The AWWA C110 committee considered the ANSI/ASME pressure ratings too conservative when used on water. Through burst testing they determined flanges and fittings made from high strength cast iron and with dimensions conforming to ANSI/ASME B16.1 Class 125 could be rated for a working pressure of 250 PSI with at least a 3.0 safety factor. This allows Class 125 cast iron flanges and flanged fittings to have the same pressure rating as Pressure Class 250 ductile iron pipe.

AWWA C110 does not address ANSI/ASME B16.1 Class 250 cast iron flanges or flanged fittings that have a 300 to 500 PSI or higher pressure rating and a totally different bolt pattern than Class 125. Mistakes sometimes occur because cast iron or ductile iron flanged fittings have “250” cast in them (indicating a 250 PSI pressure rating) but the flange dimensions and bolt pattern conform to ANSI/ASME B16.1 Class 125 (or ANSI/ASME B16.42 Class 150). These will not bolt to an ANSI/ASME B16.1 Class 250 flange!

Valve Pressure Ratings
ANSI/ASME B16 and AWWA C110 pressure ratings are based on flanges and flanged fittings conforming to standardized geometry and dimensions, including wall thickness. By comparison, valves are available in countless types, shapes, configurations and geometries that vary from one manufacturer to the other.

While the valve’s connecting flanges may conform to ANSI/ASME B16.x dimensions, there are many reasons why its pressure rating may not be the same as a flange or flanged fitting made from identical material as the valve. It is the responsibility of the valve manufacturer to establish the pressure ratings for their products. The design professional should consult the manufacturer’s published information and not assume it is the same as the flange or fitting being bolted to it.

However, the pressure ratings of many ANSI/ASME B16.x flanged valves used in waterworks service are defined in AWWA standards applicable to that type of valve. The pressure rating (or Pressure Class) listed in the AWWA valve standard may or may not conform to the ANSI/ASME B16.x or the AWWA C110 pressure rating, leading to even more confusion.

The AWWA "valve" standards which define a Pressure Class or pressure rating are too numerous to detail in this commentary but include C500 gate valves, C504 butterfly valves, C507 ball valves, C508 check valves and C517 eccentric plug valves. The design professional should become familiar with the applicable AWWA valve standard and select the pressure class that is adequate for the working pressure and be aware that the valve’s pressure class and connection flange class may not correspond.

One should remember that “a chain is only as strong as its weakest link” so every component of a piping system should be able to withstand the highest pressure that could be realized at the location where it is installed.

It’s hoped the above sheds some light on the pressure ratings for flanges and flanged valves. GA Industries LLC factory engineers will be happy to provide assistance on any specific application involving our valves.

 

[BigInch]

curtis, good work digging that one up, but it still gets worse. API flanges and large diameter flanges will throw another spanner or two into that mess.

We will design everything from now on using only S.I. units ... except for the pipe diameter. Unk. British engineer

 

[rconner]

Curtis has indeed provided some generally good historical information. Actually, it is also kind of hard to divorce the chosen gasket style (and maybe even bolts) also from the discussion of flanges, ratings and pressure etc. In this regard, I think in 2003 AWWA added a forward and footnote to many tables with regard to AWWA ductile iron flanges only (I think which are generally flat-faced) to the effect, "The scope of the standard was amended and Tables 12 and 15 through 19 were footnoted to recognize that 24-in. (610-mm) and smaller flanged fittings may be rated for 350 psi with the use of specially designed gaskets, either ring or full-face, using annular rings molded into the gasket to improve performance as recommended by the manufacturer."
This rating, with the use of such special gaskets only, of course matches the maximum standard 350 psi pressure rating of AWWA ductile iron pipes (though manufacturers can be/and have been consulted for higher pressure requirements).

 

[rmw]

ASME B31.1 has a good flange/gasket compatability listing in table 112.

rmw

PS: I'd be surprised if your pump manufacturer will put RF on 250# flanges, so if they are FF, you need to adhere to (A) above in the OP.

rmw

 

[JLSeagull]

MSS SP-6 and ASME B16.1 could help with cast iron. My copies and iron work is very old. It looks like flat and 1/16" RF could apply to all iron works and gray iron and bronze products eliminate 1/4" RF and ductile iron may be included. Other places mention 0.06-inch, smaller RF.

The flange text change seems good. I use the organization acronym like ASME and not reflect ANSI. Consider a pipe size like NPS 2 instead of 2" and flange class 300 RF not 300#.

Perhaps ASME B16.5 only mentions the Class 150 interface to Class 125. B16.1 shows shallow RF at Class 250. 6.2 states:
(b) Class 250 flanges and flanged fittings shall have
a 2 mm (0.06 in.) raised face of the diameters given in
Table 6 and finished in accordance with MSS SP-6. The
raised face is included in the minimum flange thickness
and center-to-face dimension.

Cast iron is rare for me.