API Inspections on Expansion Bottles

[ej25]

Hey guys,

I am currently working on a plan for required tank and pressure vessel inspections throughout the plant and I had a question for the expansion bottles. Basically, we have these 1 inch lines that connect to a rupture disc which then vents to a small carbon steel expansion bottle when ruptured.

My question is, do these small bottles fall under the jurisdiction of API 510 inspection - meaning external, internal, and on-stream inspections? API 510 seems to define these expansion bottles as out-of-service equipment as they rarely (if ever) see process fluid. In that case, the interval for inspection is based on the years of actual service. However, these expansion bottles are technically always in service, but rarely see process fluid.

Thanks in advance.

 

[Duwe6]

[puts my 510 hat on] I would be happy with thicknesses and call the Inspx an 'On-Stream in lieu of Internal' per 510 6.5.2(?). That assumes that the R/D's haven't blown, or if they have that the fluid is benign to the steel the bottles are made of. Typical use is on liquid chlorine or liquid ammonia lines, and [if dry] don't hurt plain carbon steel.

Otherwise, I'd stick a "SeeSnake" camera into the bottle(s) that have had the most R/D's blown, and UT-T the areas that looked the worst on the scope. If those bottle look good, sign off the rest based on 'Similar Service' and be done. Simple, easy, fairly fast Inspx of a simple item.

 

[ej25]

@Duwe6, it is for dry liquid chlorine so it should not not be a problem. I think we will stick to UT on the bottles. I've read through 510 and it does not stipulate any requirements on hydro testing pressure vessels. Is this required or more of a suggested practice every so often?

 

[Duwe6]

Hydro is actually a poor idea. Standard practice is to never reperform the hydro, unless the vessel has been Altered in a manner that the design calc's have changed.