Boiler Safety Valve Discharge piping
Boiler Safety Valve Discharge piping
(OP)
Dear all,
Please see attachment for my query related with discharge pipe routing of PSV on a 70BarG Boiler Drum.
There are two PSV's on the drum and outlet piping has to be connected to a Silensor to meet the environmental sound limits.
As there is a limitation (approved by law for this project) on the maximum height of the structure, the PSV discharge piping has to go below the PSV nozzle so that it can be connected to the silensor inlet.
My Queries are
1) Is it prohibited to do a discharge pipe routing like this (see attachment http://files.engineering.com/getfile.aspx?folder=e...) for a HP PSV discharge piping provided the discharge pipe routing satisfies the max. back pressure of 10% ?
2) Is there any safety concerns for this type of pipe routing ?
Appreciate your expert insight in this
Thanks
Please see attachment for my query related with discharge pipe routing of PSV on a 70BarG Boiler Drum.
There are two PSV's on the drum and outlet piping has to be connected to a Silensor to meet the environmental sound limits.
As there is a limitation (approved by law for this project) on the maximum height of the structure, the PSV discharge piping has to go below the PSV nozzle so that it can be connected to the silensor inlet.
My Queries are
1) Is it prohibited to do a discharge pipe routing like this (see attachment http://files.engineering.com/getfile.aspx?folder=e...) for a HP PSV discharge piping provided the discharge pipe routing satisfies the max. back pressure of 10% ?
2) Is there any safety concerns for this type of pipe routing ?
Appreciate your expert insight in this
Thanks





RE: Boiler Safety Valve Discharge piping
I would not recommend the sketched arrangement at all, this will cause problem even though you may provide drain for condensation on the lower section of the piping. More elbow numbers will increase the losses, this will increase the backpressure of the drum safety valve. This may require sometimes special large safety valves to meet the backpressure requirements.
RE: Boiler Safety Valve Discharge piping
The piping layout is unacceptable. It creates dead leg where liquid will certainly accumulate and impede relief capacity/capability. As pointed above, vibrations will also be significant.
As a general rule, silencers and other devices that could potentially get plugged and block or reduce relief flow, should not be installed in the PSV discharge pipework.
Dejan IVANOVIC
Process Engineer, MSChE
RE: Boiler Safety Valve Discharge piping
Believe this practice of using silencers on boiler PSVs' in the steam industry is common. A bypass backup bursting disc around the silencer would be a good idea, in case the silencer is corroded. Would suggest some CRA material for this silencer also.
RE: Boiler Safety Valve Discharge piping
Your routing could develop dangerous slugs of water that could tear the system apart and kill people
You need to be ready to testify in court how you were reluctant to challenge the maximum height restriction and how your MBA boss pressured you into making this bad decision.
"saplanti" gives good advice ...
MJCronin
Sr. Process Engineer
RE: Boiler Safety Valve Discharge piping
If this boiler was in an ASME jurisdiction, then you wouldn't be allowed to install a muffler (ref: ASME Sec I, PG-71.4). Be aware that the rules for steam boilers are different from those for pressure vessels - that's true in EU countries and in ASME jurisdictions. For example, the pressure drop rules don't apply to steam boiler applications. Instead, the ASME Sec I rules prescriptively state that there must be as little as possible piping on the inlet and outlet side. ASME Sec I allows a muffler on boilers that operate at low T & P, but not for "high-temperature water boilers" which operate at a pressure greater than 160 psi or a temperature over 250F.
Boilers in EU countries and those in ASME jurisdictions must be inspected and approved by an independent boiler inspector. Even without the muffler, I don't think any boiler inspector would approve a line pocket like the one shown in this installation. That pocket creates the dangerous possibility of the line being plugged in the wintertime due to ice, and/or the possibility of a "steam explosion" caused by high temperature steam mixing with water trapped in the pocket.
RE: Boiler Safety Valve Discharge piping
I knew from the beginning that this discharge piping arrangement is not the recommended way and to reaffirm my thoughts i presented it before you guys and BTW the sketch i presented was only one of the last resort options.
As don1980 said this is for EU.
Once again thank you guys
Regards
Farishta
RE: Boiler Safety Valve Discharge piping
If you do not confirm with calculation, you will be upset in the first operation, it does not matter if the project is in the EU or anywhere else in the World.
RE: Boiler Safety Valve Discharge piping