Long Bolt Flanges - Safety Issues

Well the valve mfg would have specified the bolts to be used for mounting the flange. You should follow those for safe operations

Look for 'piping standards' within the operator's standards libraries.

if u can provide picture than there will be good idea comes in mind but usually collars are provided over a coupling to protact near by operator when bolt shears from flange...

I do not have access to any of the applicable codes at the moment so please do not design a piping system around this comment, but I can see no reason why "long bolts" should differ materially from standard flange bolts for the same piping class. If your spec for the normal flanged joint bolts in a system was A193 B7 bolts and A194 2H nuts then I would imagine that your spec for the "long bolts" would be identical. (Except the length of course).

Hi all - thanks for the comments.

The issue of long bolt flanges arises from an audit finding, where it was stated that long bolt flanges are more susceptible to increase the rate of fueling a fire than conventional flanges. In this regard, I am looking for information to back up the current practise of using long bolt flanges - ie these are no more dangerous than normal flanges.

My request was to check if anyone was aware of specifications etc that forbid the use of long bolt flanges.

I work for Hydratight in the UK. We provide assistance in bolting of flanged joints for the oil and gas industry. You need to know all sorts of data before plunging into torquing up a joint as you could easily over stress the bolts and cause them to exceed their elastic limit. You could also damage the seal/gasket you are using.

You need to consider what size flange you have, material of flange/bolt/nut/gasket, amount of bolts, size and length of bolts and nuts and what method you are going to use for tightening. I have only worked at the company for a couple of weeks so cannot help you out - and the company charge a fee for this sort of work so cant go into any more detail.

Visit the website www.hydratight.com for more info. There are basic tools on there in the form of an online calculator called 'boltup' which can be used free of charge.

Hope this all helps

Kind Regards

Kevin Brown

If you use standard flanges, such as ASME B16.5-1996, you can see:

- Table 8 "Template for Drilling Class 150 Flanges"

- Table 11 "Template for Drilling Class 300 Flanges"

- Table 14 "Template for Drilling Class 400 Flanges"

- Table 17 "Template for Drilling Class 600 Flanges"

- Table 20 "Template for Drilling Class 900 Flanges"

- etc.