Custom Flange Design and Gasket Requirement
Custom Flange Design and Gasket Requirement
(OP)
From PV Elite, gasket material m and y values are required to determine the bolt area.
1) Can custom flange be designed to appendix 2 asme sec VIII div 1 without knowing the gasket (m and y values)? The flange thickness and number of bolts seem to have an effect on this.
2) For standard flanges, are they designed to any reference gasket (reference m and y values)?
Thanks.





RE: Custom Flange Design and Gasket Requirement
It is the other way around. Custom gaskets are seldom made (and are very, very expensive!) but can be ordered.
Standard gaskets are made by the tens of thousands to fit and work with standard gaskets, standard bolting patterns and standard bolts to allow for a specific temperature, pressure, metal and fluid combination needed.
RE: Custom Flange Design and Gasket Requirement
Standard flanges such as B16.5 are wholly different animals and do not use Appendix 2 methods, at least explicitly. Not to say you can't run a standard flange under Appendix 2, but it may or may not make.
Regards,
Mike
RE: Custom Flange Design and Gasket Requirement
1) To reiterate, since gasket m and y values affect flanges in appendix 2, Appendix 2 cannot be used without knowing gasket information? Please correct me if I am wrong. The reason is because client sometimes do not specify gasket requirement and ask us to design custom flange.
2) Do gasket m and y values affect standard B16.5 flanges? In order words, is there a restriction on what gasket (m and y values) can be used for standard B16.5 flanges? I am not able to find the restriction on the gasket m and y values for the standard flanges.
RE: Custom Flange Design and Gasket Requirement
2) B16.5 does not use m, y values for establishing the flange ratings. Gasket types are somewhat restricted by bolting strength. Recommend you get a copy of B16.5 for your reference, as it is not really possible to go into all details in a forum.
As well, recommend you study Appendix 2, to better understand the design process.
Regards,
Mike
RE: Custom Flange Design and Gasket Requirement
That depends on the gasket. Gaskets that can be cut from sheet-gasket materials are readily available, with prices varying depending on the material cost. So a rubber-type flat gasket in custom sizes is no problem, something like a spiral-wound gasket would be a different issue.
RE: Custom Flange Design and Gasket Requirement
Larger manufacturers will generally have applications engineers on staff to assist with selection and design. Smaller shops, not so much.
Regards,
Mike
RE: Custom Flange Design and Gasket Requirement
B16.5 recommends that certain hard to seal gaskets should not be used with 150# flanges. There is a table somewhere in the back that lists which ones should / should not be used.
RE: Custom Flange Design and Gasket Requirement
Indeed in the Taylor-Forge / ASME method the concept of effective width means you calculate on a less than actual contact width and often under-calculate the load, which leads to things like Appendix S which allow you to thrash the bolts up a bit more if need be… Consequently most bolt workers aim at 40-50% bolt yield or more on-site, compared to say 25,000 psi as the typical design stress of the good old B7 bolt…. The required bolt load from other design codes such as the old DIN 2505 or EN1591 (which is at least based on gasket load-leak and creep data), or even the PVRC method would all usually give greater loads than m & y.
The custom gasket is probably not as expensive as some might think, though is often badly specified and over-looked until it is then also badly installed at the wrong load. At this point you develop a leak and the plant then spends thousands on leak repair clamps, and tries to investigate why it leaked and tries different gasket types from several manufacturers in an attempt to resolve it…. Make sure that you balance the actual gasket stress requirements against what the flange and bolts can give, and beware things like thermal differential growth between flange and bolts etc - EN1591 at least accounts for this where ASME does not.
RE: Custom Flange Design and Gasket Requirement
Regards,
Mike
RE: Custom Flange Design and Gasket Requirement
RE: Custom Flange Design and Gasket Requirement