Valve placement for maintenance
Valve placement for maintenance
(OP)
A piping contractor recently made a comment on our piping saying that we should add a spool piece in between valves for "maintenance purposes". Has anyone else heard of this? If the valves allow I have always put them flange to flange to avoid extra pipe and fittings.





RE: Valve placement for maintenance
RE: Valve placement for maintenance
what type of valves?
Access and operability of the valves ( handles clash etc) would seem to me to be more important.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Valve placement for maintenance
Also if I put a 6D spool piece between valves, I can put a vent, drain, or both on the spool piece to allow for double-block-and-bleed, chemical injection, purge gas injection, or check valve testing. No one ever had too many access points to a piping system.
Finally, if I drop the spool out for maintenance and find it impossible to get it back into the space it came out of (this has happened twice to me), you can make up a shorter spool to fill the gap.
David Simpson, PE
MuleShoe Engineering
In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist
RE: Valve placement for maintenance
RE: Valve placement for maintenance
I find it best to take a moment and think about as many scenarios that I can come up with and assess to appropriateness of my desired valve placement in each scenario. What you do not want to do is increase your lifetime costs by saving a little bit of up front capital.
David Simpson, PE
MuleShoe Engineering
In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist
RE: Valve placement for maintenance
Can you give us some information about the specific situation that initiated this comment?
In the overall picture of a typical Process Plant (Refinery Unit,Chemical Plant Unit) or Power Plant there are normally not a lot of Valve to Valve situations.
Sometimes its possible to do all the right things and still get bad results
RE: Valve placement for maintenance
RE: Valve placement for maintenance
We are constantly getting beat up for reducing our fitting counts and welds in our design. Although I see you point to this I think it would be a bigger deal to have to answer to why we added 2 more welds, pipe, and two fittings and an extra gasket if not needed.
It also surprised me that the contractor brought up this comment and not the plant maintenance guys. We have done work on multiple plants for this client and it has never been mentioned in the past. There was some talk about the bolts are difficult to put in and take out. I wonder if it is more of a inconvenience that they cant use a air gun to tighten all of these valves during fabrication?
RE: Valve placement for maintenance
My priority will always be maintainability. I really want to take every one of those KPI-spewing idiots and put a wrench in their hands in a driving blizzard, standing on a frozen mud hole that will always thaw enough to break the first time you are in an awkward position. I've never been able to, but I've always dreamed of it.
David Simpson, PE
MuleShoe Engineering
In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist