Thickness calculation for high temp service, Div. 1 vs B31.3
Thickness calculation for high temp service, Div. 1 vs B31.3
(OP)
All,
Div 1, UG-27 does not have weld joint strength reduction factor (W) to calculate thickness while B31.3, para 304.1.2 does for high temperature service.
For stainless steel at 1450 degF, the reduction factor 'W' is 0.545, which means B31.3 will have twice of the thickness than Div 1.
1). I am making my 48" OD x 150' long pipe (304H SS at 1450 degF) to be designed and fabricated per Div. 1, not B31.3. Doing that, the thickness is 1" per Div 1 instead of 2" per B31.3, that will save a lot of money and improve schedule (not just saving the material and welding, but also support system and foundation design). Any problem ?
2). In the above real case, the weld metal is normally 308H. If I am forced to go by B31.3, can I use 16-8-2 weld metal, which has better creep rupture property than 308H weld metal and 304H base metal, and take W=1 instead of 0.545 so I can still get 1" thick from B31.3 ? Has anyone have the experience ?
Jeff
Div 1, UG-27 does not have weld joint strength reduction factor (W) to calculate thickness while B31.3, para 304.1.2 does for high temperature service.
For stainless steel at 1450 degF, the reduction factor 'W' is 0.545, which means B31.3 will have twice of the thickness than Div 1.
1). I am making my 48" OD x 150' long pipe (304H SS at 1450 degF) to be designed and fabricated per Div. 1, not B31.3. Doing that, the thickness is 1" per Div 1 instead of 2" per B31.3, that will save a lot of money and improve schedule (not just saving the material and welding, but also support system and foundation design). Any problem ?
2). In the above real case, the weld metal is normally 308H. If I am forced to go by B31.3, can I use 16-8-2 weld metal, which has better creep rupture property than 308H weld metal and 304H base metal, and take W=1 instead of 0.545 so I can still get 1" thick from B31.3 ? Has anyone have the experience ?
Jeff





RE: Thickness calculation for high temp service, Div. 1 vs B31.3
RE: Thickness calculation for high temp service, Div. 1 vs B31.3
RE: Thickness calculation for high temp service, Div. 1 vs B31.3
This is for a real petrochemical project that produces gasoline from crude oil. Everything I deal daily is all real project, from design, procurement, fabrication to construction. I have been doing pressure vessels and piping stress analysis since 1990 in a big engineering company in Houston. Normally I do not have problems with codes since we have to comply. Once a while, there will be a hipcup, just like PWHT I posted in another thread and this one.
Jeff
RE: Thickness calculation for high temp service, Div. 1 vs B31.3
"The design pressure is 60 psig. B31.3 for piping..."
Uh, yeah, problem
RE: Thickness calculation for high temp service, Div. 1 vs B31.3
If you are designing a pipe line, stick with the B31.3 code.
RE: Thickness calculation for high temp service, Div. 1 vs B31.3
RE: Thickness calculation for high temp service, Div. 1 vs B31.3
RE: Thickness calculation for high temp service, Div. 1 vs B31.3
There is no need for anyone to run the thickness and pont out my thickness calc is wrong or material is not suitable, which is irrelevant to my (2) questions. The twice of the thickness from B31.3 is the true fact, that costs a lot. I have been thinking Div 1 is more stringent than B31.3, but not true for PWHT and high temp service.
RE: Thickness calculation for high temp service, Div. 1 vs B31.3
RE: Thickness calculation for high temp service, Div. 1 vs B31.3
RE: Thickness calculation for high temp service, Div. 1 vs B31.3
RE: Thickness calculation for high temp service, Div. 1 vs B31.3
ASK your client which they would prefer it to be. Sure, the captial cost will factor into the equation, but it's not the sole consideration.
RE: Thickness calculation for high temp service, Div. 1 vs B31.3
RE: Thickness calculation for high temp service, Div. 1 vs B31.3
I opt for Div 1 not only saving the cost, but it has more piping flexibilty by less thickness that will ease the loading at the ends connecting to vessel and rotating equipment.
Since there is no wled strength reduction in Div. 1, my real concern is the girth seam that will see the longitudinal bending stress from sustained loads (pressure+weight). Do I need to consider weld strength reduction for the girth seam when I run the pipe stress flexibility analysis(which means allowable longitudinal stress will be redcued by almost 50% in my case)? Can I use 16-8-2 weld metal (costs more) and ignore the weld strength reduction so I can easlily qualify the pipe stress analysis ?
Anyone has done so ?
RE: Thickness calculation for high temp service, Div. 1 vs B31.3
Regards
rhg