Hi to you knowledgeable people of the welding industry.I was a bit puzzle when I saw a contractor fabricate and install an 8" carbon steel pipe line, (approx. 100 m long),transporting steam from a boiler to the brewery in the factory where I work.He cut a 6" beam along the web,used the pieces as shoes for supporting the pipe off the pipe rack.The pieces (12") long were welded to the bottom of the pipe.Is this the correct procedure for these pipe brackets?Isn't welding or even striking the arc (beside the joint)along a high pressure pipe unacceptable?Steam is at a temp.150 degrees C or above and approx. 10-14 bars psi.what's your view on this.what type or design of brackets should be used?
Hi!
First off all, It really depends on what the 'client' requires and the 'spec' your working to!
However, given what you've told 'us', I would say this is an acceptable practise,if complimentary NDT where to be preformed on the fillet weld to the 'pressure envelope'.
An alternative to this practise, is to 'weld' a 'doubling' plate onto the pipe and then 'weld' the support onto the 'doubling' 'plate' This would still need relavant NDT(MPI,DPI).
Regards
Personally, I've always considered that welding on pressure pipe is not to be considered a Good Engineering Practice.
However, years ago I took part in the erection of an oil refinery whose basic engineering had been performed by such a prestigious firm as The Lummus Company. Also, I took part in the detail design of a petrochemical plant whose basic engineering had been performed by such a presigious company as M.W. Kellogg. In both cases, either Lummus and MW Kellogg allowed to weld a "shoe" (as you say), to the pipe to support it on the rack, WITH NO need to submit the weld to NDT. I didn't like the arrangement, but as the basic engineering companies allowed it, there was nothing I could do.
Personally, I prefer to weld the shoe to a clamp bolted to the pipe, but this is a personal preference that highly reputed companies as Lummus and MW Kellogg don't take into account.
Giovanni S. Crisi
Sao Paulo - Brazil
Supports are welded to steam lines all the time.....Even high pressure lines. In steam systems of high pressure steam boilers (above 250 degree & above 150-psi) such as a power plant using steam to run the generator(s), supports, such as the tee bracket or "shoes" are an intregal part of the system as so much heat is generated that the steam (& condensate) lines actually "grow" meaning, expand to allow the steam system to work properly, in fact somewhere on the line there is an anchor point which involves a heavy duty hanger is fabricated so all growth of the system is controlled (or beginning from that specific point.) Also, expansion loops are typically required as well to allow for expansions at certain points depending on how long the pipe lines are.
I am not an engineer, but I have been around enough power houses to see this done to know that it's all engineered into the system.
Hope that explains things somewhat.
Forum
