08.11.2013.....from another thread
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RGY....thanks ..I understand the relief valve construction  ...

1. what is the intended steam relief valve setting?
2. is this governed or dictated by the discussions you held with the boiler inspector...prior to construction?
3. do you use the manual water pump to hydrostatically set the relief valve?
4. are you going to place the RED line on the boiler pressure gauge?

The reason I ask this last question is that I damaged a 1" pressure gauge ....[I think beyond repair  ] in my attempt to remove the gauge outer bezel to inscribe the 45 PSI RED line marking......Derek

Hi PD's.....not to be baulked with this and after ZERO response from Miniature Gauges UK  .........I have discovered

1. the lower tapping in the rear of these miniature brass cased gauges is in fact a 10 BA jacking screw tapping
2. by screwing a 10 BA brass screw impinges or contacts the inner face of the gauge dial
3. by continued rotation of the 10 BA screw the case bezel is displaced however it may have caused further damage to the burden tube hair spring
4. it also pops the needle pointer off the spindle 

To cut a long storey short......I have stripped two gauges, marked the RED line & reassembled them.......

5. now to see if they still work....... ......Derek

I hope one works for you Derek. Geoff   

Why not just mark the line on the glass?

Charles........marking the glass would not be indelible with steam & oil.....although it does appear to be acceptable [within the Standard] to scribe a line on the bezel case & infill that with RED paint/marker................ Derek