spiral welded pipes 1

[etrobal]

i was tasked to review the applicability of spiral welded pipes (swp) to our system as these swp's are cheaper than our requirements, which are seamless and/or single longitudinal welded pipes.

consider our design parameters (depending on the fluid):
6.60 mpag at 282degC;
7.72 mpag at 294degc;
2.14 mpag at 216degC;
1.72 mpag at 208degC;
1.08 mpag at 183degC;
3.15 mpag at 222degC;
3.86 mpag at 198degC;
3.31 mpag at 198degC and
1.38 mpag at 198degC.

from my surfing some websites, swp's are mainly used for piles, supports, water ducts and the like. there is no mention (or did i miss a website??) that swp's can be used for high pressure, high temperature applications.

can somebody please direct me to a website where a plant uses swp's similar to our applications?

if a plant is authorized to use the api 5L monogram, is it safe to assume that the plant does not manufacture swp's?

is the power piping code b311 applicable also to swp's? does the b311 allow the use of swp's?

can i recommend the use of spiral welded pipes in our application? note that we usually have stub ins, pipe shoes that might compromise the spiral welds. or will such connections have an effect on the integrity of the spiral welds?

thanks and am looking forward to your advices and comments. (i posted this in the mechanical forum)

 

[JohnBreen]

etrobal

There is no substitute for a competent and responsible piping engineer. The lives of plant employees and the public depend upon the design of piping systems. Environmental issues are also involved in choosing the appropriate piping materials and products.

There are Code limitations on how spiral longitudinal welded pipe can be used. It is NOT only the ASME B31 Code for Pressure Piping, B31.1, Power Piping that includes these limitations. You really need to READ THE CODE that is mandated by the jurisdiction in which the piping system is to be built.

In B31.1, read paragraph 102.4.3 and study Table 102.4.3. If the owner specifies that the system is to be designed, fabricated, erected, inspected and tested to the requirements of the ASME B31 Code for Pressure Piping, B31.3, Process Piping, read B31.3 paragraphs302.3.4, 328.4.3, and study Table 341.3.2.

Regarding your pressure/temperature ratings, look up the weld joint efficiency coefficients and do the math involved in determining the minimum required wall thickness (and check the requirements for NDE and testing). All things considered, you may not realize the economies that you are projecting.

A competent piping engineer must match the application to the pipe that is specified. Learn about piping specifications. You might start here:

http://www.klsteel.com/sdp/229183/4/pd/543899.html

if a plant is authorized to use the api 5L monogram, is it safe to assume that the plant does not manufacture swp's?

No.

can i recommend the use of spiral welded pipes in our application? note that we usually have stub ins, pipe shoes that might compromise the spiral welds. or will such connections have an effect on the integrity of the spiral welds?

I think you already know the answer to this question(s). Explicit Code rules for the design of fabricated branch connections (reinforced or unreinforced) are provided and there are requirements that are to be met if an opening for a branch connection cuts through a longitudinal weld (including spiral longitudinal welds). The Piping Codes are NOT design manuals, ultimately the piping engineer is responsible to the owner and to the jurisdiction for the design (including the effect on weld heat affected zones that are reheated during the fabrication of the system). Demonstrating that a failed piping system design did not violate the letter of a piping Code will have no merit in a criminal or civil court case - the liability is that of the designer and his/her employer.

Respectfully, John

 

[KevinNZ]

We use SWP for steam duty all the time. Cost effective for larger diameters. But we are sure to pruchase from manufactures who comply with the pipe manufacture codes. E.g API 5L.

 

[MJCronin]

"You really need to READ THE CODE that is mandated by the jurisdiction in which the piping system is to be built."


Amen....John

More power to you....

Mike Cronin

 

[etrobal]

thank you for your valuable inputs, comments and recommendations. appreciate it very much indeed.

 

[JLSeagull]

I have never been on a project that permitted spiral welded pipe and was unaware that anyone still used it. About 34-years ago I was working in a refinery HF alkilation unit when I heard a muffled explosion. It turned out to be a spiral welded pipe that was being repaired about 100-foot from where the pipe blew out.