pipespec for methylamines
pipespec for methylamines
(OP)
There are many professionals out there, does anybody know anything about methylamines?
I work since a few months with a company that produces methylamines (monomethylamine, dimethylamine, trimethylamine etc.)and I don't thrust their pipespecs.
des. temp. 230 deg C, des. press. 20 barg.
What valves and what material should be used.
What pipesched., what connections?
greetings, a guy from Europe
I work since a few months with a company that produces methylamines (monomethylamine, dimethylamine, trimethylamine etc.)and I don't thrust their pipespecs.
des. temp. 230 deg C, des. press. 20 barg.
What valves and what material should be used.
What pipesched., what connections?
greetings, a guy from Europe





RE: pipespec for methylamines
http://virtualpipeline.spaces.msn.com
RE: pipespec for methylamines
That´s not my concern, but the fluid/gas seems to be very volatile and smells a lot.
The spec is ss316L, I think that´s good.
But they use buttweld bellowsealed globevalves as a first choice, they couldn´t explain why.
What should it be?
Everywhere are leakrepairs on the valves and the seats are wearing very fast.
I suggested flanged bellowsealed gatevalves but they won´t listen to me.
Am I wrong?
(i´m just a contractor)
Thanks for your reply
RE: pipespec for methylamines
It sounds like the globe valves are not holding up, perhaps due to improper seat material, or is it from high velocity? Are they control valves or on/off? If for control purposes, that may explain why they use globes and why substituting gates or balls would probably not be a good idea. If that is the case, other material, antiflash trim, or simply larger valves may be the solution.
Too many unknowns to suggest a solution, but perhaps it could be possible to use weld-end top entry valves, if they are in on/off service.
http://virtualpipeline.spaces.msn.com
RE: pipespec for methylamines
Hello europipe,
What are your actual pipe and valvesizes?
Seat and stem sealing material (seat metal to metal or other)? How does the fluid behave when colder (sticking, gluing, abrasive), and does a colder temperature occur sometimes during process or at regular stops? Are the pipelines cleaned out and washed (CIP) with other fluids/temperatures and pressures?
Disregarding answer to above, if smaller size valves are used, then y-type globevalves sometimes have a longer and better protected and sealed stem than normal globe - valves, less force 90 degree on stem (?), and more often stem scraper incerts protecting part of stem to enter stem sealing area.
If abrasive or gluing, sticking and drying fluid anywhere (or when) in the process, globe valves would in general be the best choice, preferably with metal to metal seat.
If high maintenance cost and often occuring leakage, you could even for on/off duty check if a regulating type of globevalve could give a better economy over lifetime.
I am thinking about a construction for instance with globe part slotted, open ended cylinder form and protected (innerside of cylinder) metal seat, or similar constructions.
RE: pipespec for methylamines
in 95% of the cases on/off usage.
They are wearing very fast (also the hardseat type), most likely because of the high velocity.
Why should you use valves with such a low Cv-value?
Uhhm...I´m contractor of piping eng. work.
RE: pipespec for methylamines
pipesizes up to approx 4"
not sticky stuff, volatile medium, boiling point average 0 degC, saets metal to metal(des temp 230degC)
not very cold temps no flashing.
there are also y-type valves but they wear even fast
washing out by water and dried by nitrogen.
Why should you use globevalves?
greetings
RE: pipespec for methylamines
http://virtualpipeline.spaces.msn.com
RE: pipespec for methylamines
europipe,
OK! So this seems to give no other cause for the wear than high velocity? If so, I agree with full port solution.
But what are the high velocity - typical at nominal pipe-size?
RE: pipespec for methylamines
I´m really not a process engineer but I think the max velocity is about 3 m/s, that is I think normal for a pipe,
but in a globe valve with it´s constuction?
I think the valves also causes the pump startup problems they have, is that possible?
RE: pipespec for methylamines
3 m/s is normal both for pipe and for any valve, including a globe-valve, if else adapted for the temperature, pressure class and medium, (and fluid viscosity - and non abrasive fluids or particles at any time, including cleaning) and should in itself not cause wearing problems.
If yes for the latter, the problem could be caused by the former.
Only speculating but: If hammering /shutterings problems could be lay-out of pipeline and/or oversized or type of check valves. What about two-phase (gas and fluid phase) in pipeline, or (perhaps most probably?) nitrogen residues giving 'non evacuated air pillows - compressible' acting as 'springs' when you start pumping fluids (???)
Cleaning with water at what pipeline and water temerature (chock -chilling)?. No particles (non-abrasive) when cleaning and drying?
RE: pipespec for methylamines
http://virtualpipeline.spaces.msn.com
RE: pipespec for methylamines
Different pumpproblems: some pumps are turning backwards,
isn´t that funny.
It´s a great company for a laugh here.
RE: pipespec for methylamines
Backwards? Its probably because the valves are too small.
http://virtualpipeline.spaces.msn.com
RE: pipespec for methylamines
I was not sure but you confirmed what I thought
Greetings & Nice holidays