Valves for Use in Fuel Gas Having Black Powder Content 1

[drywall]

Our client has requested us to provide about 1500 meters of 4" pipe from the hot tap, into an existing 20" fuel gas line, all the way to a metering station. The service will be fuel gas (primarily methane) and unfortunately there is a problem with black powder. As I understand it, the black powder is the by product of components of the gas stream reacting with the interior pipe wall. We have not been asked to coat the inside of the 4" pipe but rather to provide filters upstream of the gas meter and to specify valves which resist black powder erosion. Even though the Internet is full of articles about black powder, we haven't been able to find anything about the proper valves. Does anyone else have experience with the same or a similar issue?

 

[CostasV]

I can think of two problems that black powder causes to the valves.
First, (when the valve is open) the particles of the black powder hit at the sealing surfaces, and second (when the valve is closed), the particles of the black powder sit between the sealing surfaces leaving small quantities of gas to leak to the other side of the valve.

Though I work in gas transmission company that has coped.... quite a few tonnes of black powder, I haven't heard of "black powder resistance" valve yet.

Filters and/or cyclons is the usual solution.

 

[drywall]

Varsamidis, Thanks for the post. I have been out of the office for a few days and am late in seeing your response. Do you have any recommendations for filters or cyclones?

 

[CostasV]

Not exactly recommendation, just a worth-saying situation for the filters.

Though, our specification for the filter welds, was 100% examined by radiography, there were some weld inside the filter that was not possible to be radiographed, due to the way the filter was constructed.
Actually, there was not even welded at all.
There was a gap (inside the filter) not easily seen, about 10 cm long, 2 mm wide, that let gas escape without being filtered.

Lesson (for us) to learn: When I see 100%, I search a little more.