What grade of metal to use for boiler gauge glass body
|Mike Henderson 1||23/07/2021 23:26:59|
|28 forum posts|
I have to make the bodies for a pair of reflex gauge glasses (sometimes called Klinger glasses). The machining operations are pretty straightforward but I'm uncertain what grade of material to use.
The options are phosphor bronze PB1, the same but PB102 or leaded gunmetal LG2, all in drawn form, not castings.
Which would be best for machinability and which for corrosion resistance, bearing in mind the duty to which they will be put? For clarity, no soldering, hard or soft is involved. Machining will be mostly milling, plus some drilling and tapping.
I'm looking at 2 1/2" diameter bar here, so would like to get it right first time. The finished bodies will be highly polished and see service around 200 days a year.
Thanks in advance.
|Jon Lawes||27/07/2021 06:33:07|
636 forum posts
PB102 for me.
|duncan webster||27/07/2021 10:36:32|
|3456 forum posts|
Drawn bronze can be a right pig to drill and tap
|Mike Henderson 1||29/07/2021 08:31:54|
|28 forum posts|
Thank you, Duncan and Jon.
I've had previous with phosphor bronze, in particular the grade that is very red in colour. Not sure what exactly it was - stores issue half a century ago when I was young and ignorant. Drawings called for a length to be press fitted into a steel housing, bored and then reamed to size 1" diameter x 6" long. Anyone see a disaster waiting to happen?
Enough to say that it was fortunate it was a through hole as the reàmer had to be drifted out and was probably ruined.
Some research has revealed LG2 is stated as not subject to dezincification and often used for (cast) steam valve bodies rated in excess of 200 psi. The gauge glass bodies I'm making will be working at 150 psi so material should be suitable. However, I have Jon's recommendation of PB102 so a bit more study is called for.
Thanks again, Mike
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