Hello tank experts,

I have a product line of mixers that mounts to existing storage tank nozzles. We supply the adapter flange. The vast majority use API 650 Manways or Nozzles with flat faces. Now we are expanding to customers who request raised face versions of the same. It obviously helps if we can continue to use the flat face designs we have on the shelf where practical.

If a customer has a raised face flange on the tank, can we bolt a matching flange without a raised face?

Can the flat face gasket be used between two raised faces? Can a flat face gasket be used between one raised and one flat face?

If there is an industry standard that provides guidance on these questions, I would appreciate a pointer to it.

David

If a flat-face style gasket is used, it works fine to put a FF flange onto a RF flange. There is no API prohibition on it, either. Your problems will be
1) customer reluctance to accept FF in lieu of RF
2) overtorquing, thus bending the FF 'plate' flange while mating to the thick, forged RF ANSI/ASME flange.

If I liked the price difference you could give me, I would accept it. There are many, many folks that won't, due to "We've always done it the other way". Never underestimate the inertia of old, senior Field Engineers and Superintendants.

Hm. The extra load on a raised face may give me justification to make all raised face flanges thicker than the flat-face counterpart. So on a commercial level that will encourage the use of the flat face standard design.

Correct. Typically, only the pipe nozz's on API tanks are RF. Everything else, especially M/W's use the API flat-plate design. Waaaayy cheaper and lighter [1 man can hold a 30" M/W cover up] than using ASME RF flanges. Especially since we all have access to X-Y axis plasma, laser, or Oxy-Acet burning tables. Program it and forget about it -- burn as many as needed w/o having to do any layout.