h202 service 1

[suren12564]

1.WHY BALL VALVES ARE PREFERABLE FOR H202 SERVICE...CAN I USE GATE VALVE INSTEAD OF THAT?
ACTUALLY INSTEAD OF 3/4" BALL VALVE OF ASTM A182 GR.F 316L,TRIM-SEAT-RPTFE FLANGED END 150# I WANT TO USE 3/4" GATE VALVE SW BODY ASTM A182 GR.F 316L TRIM STELLITED.. IS IT OK? THANKS IN ADVANCE?
2. CAN SOCKET WELDS PREFERABLE FOR H202 SERVICE?

 

[bimr]

Peroxide decomposes with rapid decomposition with gas evolution. Fast decomposition may also occur if the hydrogen peroxide is brought into contact with insoluble solids.

Ball valves are recommended with suitable venting arrangements for releasing potential pressure buildup from the decomposition of hydrogen peroxide trapped in the valve. Diaphragm valves can be dangerous if hydrogen peroxide gets into the bonnet, and hence the valve bonnets must be drilled. Plug-type valves need a lubricant, and therefore are not recommended.

Acceptable valves have a seat, usually polytetrafluorethylene, and a small hole drilled in the ball so that in the off position the channel through the ball is in communication with the shut-off higher pressure side.

http://www.solvay.co.th/en/binaries/H2O2_Handling and Storage-191789.pdf

Hydrogen peroxide piping should be of butt-welded and flanged construction. Under no circumstances should socket welds be used in hydrogen peroxide systems. Threaded systems are not recommended, as threaded aluminum and stainless steel piping may not maintain liquid- tight connections. However, threaded connections may be used in areas where there is little hydrogen peroxide throughout (e.g., pressure safety valve connections). Piping should be routed outdoors whenever possible, to minimize the hazards which could be created by a leak.

Follow the suppliers storage and handling guidelines.

http://www.solvay.us/en/binaries/HH-2323-236798.pdf

 

[moltenmetal]

Well...there's hydrogen peroxide, and there's hydrogen peroxide. There's the stuff used for bleaching hair (6%) , and then there's the stuff used in rocket fuel (95%)...they're not the same animal at all.

If you're using 35 wt/vol % H2O2, not 50% or 70%, you can relax a bit. It's still hazardous, but you do not need to go to he extremes listed by bimr above.

Ball valves are preferred over gate valves because a) they tend to be class VI shutoff (i.e. bubble tight) instead of class IV shutoff for a gate valve, and b) at the size you're talking about, they're also substantially cheaper.

If you want to avoid the flanges, which is what is driving the cost, get a socket-welding 3 pc ball valve. The valve internals are still serviceable by means of the valve's own flanges- external flanges aren't required. Small ball valves tend to have cavity relieving seats, so the concern about oxygen pressure build-up in the cavity of the ball valve isn't a problem until you get to larger sized valves.

 

[Latexman]

suren12564,

Most H2O2 suppliers have Safe Handling Guides. You can probably find several using Google. Some (FMC back when they still had H2O2) will give you their recommended valve and piping specifications. I recommend you take advantage of this service from your vendor, if possible.

Good luck,
Latexman

To a ChE, the glass is always full - 1/2 air and 1/2 water.

 

[suren12564]

why socket welds should be avoided for Hydrogen peroxide service?

 

[moltenmetal]

At least one reason: H2O2 systems should be self draining so they don't need to be flushed for maintenance. Socket welded piping contains a lot of crevices and does not drain well.

 

[zdas04]

Socket welds (because of those crevices that moltenmetal is talking about) are also much more prone to hydrogen embrittlement than butt welds.

[bold]David Simpson, PE[/bold]
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

 

[suren12564]

thanks a lot guys for sahring valuable information