Engineers: What Pipe Thickness Do You Specify?

9/10/2019

There's a varying degree of specifications out there - but I've never really seen it openly discussed or defended.

Some organizations (such as military, many healthcare clients) require schedule 40 for pipe 1 through 2 inches in diameter. Some engineers hardly compile specifications and place no requirements on the pipe thickness. Some projects only allow schedule 40 or even schedule 80.

If you're an engineer, what is your basis for recommending different pipe thicknesses for different clients? Is corrosion the only reason why the thicker pipe diameter is specified for your clients?

Would be really interested in understanding the reasoning (one way or another) for specifying different pipe thicknesses on suppression systems. Thanks in advance.

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5 Comments

Colin link

9/10/2019 11:10:50 am

We specify minimum schedule 10 for grooved piping, and schedule 40 for threaded. With roll groove fabrication, schedule 10 piping has higher CRR (corrosion resistance ratio) than threaded schedule 40, so it should provide an adequate protection against normal corrosion.

We're seeing roll grooved schedule 10 piping allowed on Military projects now; it's written into the specifications by way of the CRR valve, something like "piping shall have a CRR valve of 1.0 or greater after threads or grooves are added".....

Matthew King

9/10/2019 11:20:42 am

ASME B31 code methods, e.g. B31.3

☼

9/10/2019 11:29:37 am

System design is based on the clients needs and corrosion tends to be a big factor. The Fire sprinkler podcast that has a few segments that hit this topic really well. Go to the April 14, 2019 episode and skip to 27:35. They talk about system components based on client needs regarding expected longevity of the system and pipe thickness. Also go to the Jan 24, 2019 episode and skip to 31:47. They talk about type of pipes regarding corrosion in galvanized vs black. Engineered corrosion solutions and General air both have good resources online to learn more about corrosion.

Pjd

9/12/2019 05:36:24 pm

I want to add here, adding thickness isn't preventing corrosion. It only prevents leaks. You still have increased pipe roughness and obstruction from corrosion. It's like bury your head in the sand if you think it's OK as long as it isn't leaking. Slope your dry systems, routinely empty low point drains, on wet add automatic vents, implement N2 emersion or a MIC plan, and stop placating these lowest bidder wins a holes.

Matthew Virtue

9/13/2019 09:47:30 am

PJD.... The schedule of pipe doesn't prevent leaks. It delays the time corrosion will eat through the pipe.
I agree with...
"..slope your dry systems, routinely empty low point drains, on wet add automatic vents, implement N2 emersion or a MIC plan, and stop placating these lowest bidder wins a holes."

Engineers: What Pipe Thickness Do You Specify?

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