Weld Neck Flange Welded to Weldolet

Robin,

You can weld anything onto a weldolet so if you have a weld end valve then yes you can do this or directly weld a weldneck flange. There is also a product called a "weldoflange" which is a single forged flange and weldolet as one item which reduces one weld.

Of more concern though is that you're talking about welding a weldolet onto some sort of tank - I don't know what you mean by "volume tank" - it's not a term familiar to me. Normally this is called a nozzle and needs to be designed such that the additional loads on the tank are acceptable, i.e. weight of the valve and piping, other forces etc and this usually requires some sort of compensation plate on the tank to reduce stress loads. I haven't seen a weldolet put on a "tank" before, only piping or a pressure vessel, where other design codes apply such as ASME VIII or PD 5500. ditto tanks have their own design codes which you need to follow if you're going to modify an existing unit. If you're not careful you could rip a hole in the tank once you bolt everything togehter and fill it with liquid....

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

You need to consider the physical space required to operate the installed valve. Be sure to take into account insulation, if used.

Also, consider future replacement of the welded valve. Cutting, welding may involve decontamination and/or purging. Might want to use a flanged valve?

donf

LittleInch, I agree with you for the most part, i.e. on olet-fittings not being used on vessels for nozzles, except that I havent found a reference (in e.g. for VIII-1) so far which prohibits olet-fittings (weldolet, flangolet, etc.), giving me some ammo to convice people unfamiliar with vessel design why not to use them. Not that I know the Code from start2finish as some seem to here around here ..

Talking 'bout olets, vesselets are olets designed for vessels, arent they?

Vessels are a different subject. The op talks about a "tank". I think olets are ok for vessels but need to be designed and assessed properly. Weldolets are designed for piping on the replacement metal basis, but tanks and vessels have different rules. They normally need more reinforcement than offered by a weldolet, especially for larger nozzles.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way