What is the recommended pipe schedule for 220 lb steam line 2

[49830]

I am re-routing an existing 3/4" high pressure (220lb)steam line. The old line is sch 40 and appears to be badly deteriorated. Do I replace the pipe with sch 40 or do I go to sch 80. The existing fittings were 300#.

 

[TBP]

220 is likely the operating pressure. What's the safety valve setting? Assuming the safety lifts at 300# or less (and it better be, with 300# BMI fittings) I'd use sch 80 A106B. Good quality, readily available grade of pipe that usually threads nicely, as compared to other (as in crappier) grades that are normally stocked. It's somewhat more expensive that the other types, but since the labour is the same, it's pretty much a non-issue.

 

[NozzleTwister]

My recommendation is to replace with Sch. 80 ASTM A106, Gr. B and use 3000# Socketweld fittings. For flanges and flanged valves use Cl. 300, for socketweld valves use Cl. 800. For nipples between a branch or equipment to the first block valve, use Sch. 160 minimum for a robust design.

These recommendations are what I consider a minimum for this service. Temperature and corrosion allowance were not given so with complete information, you need to verify ratings and wall thickness are adequate.

Good luck,


NozzleTwister
Houston, Texas