Boiler safety valve setting procedure is given in this article. To make the content easier to understand and also to make reader to understand as how this important activity is done.
When we need To do Boiler Safety Valve Setting
Answer to this question is very simple. You need to do setting of safety of boiler in following cases:
1) Newly commissioned boiler
2) After each boiler survey.
As an engineer onboard you will be required to set the safety valve after each boiler survey. It is a process which needs precision and skill also. Let’s check the stepwise details of the procedure you need to follow while setting the valve.
Boiler Safety Valve Setting- Step Wise Procedure
1) Make sure that tools required for the setting like spanner, gagging tool etc are ready.
2) Boiler is ready to be fired. Make sure that the steam blow off line after the safety valve, have a drain and it should be unclogged and should have free passage.
3) Make sure that safety valve have been assembled properly.
4) Close the main steam stop valve.
5) The other safety valve should be gagged to prevent it from lifting. It will set later on when the first safety valve have set.
6) Start firing the boiler manually and slowly raise the steam pressure.
7) Screw down the compression nut little bit more than the previous distance. If you don’t have previous reading, then it will require little bit more attempts before you can actually set the valve.
8) Now let’s say you have to set valve at 9 bar. So, raise the pressure slowly. Just before the 9 bar, like 8.8 or 8.9, you will start seeing little bit of steam coming out of the safety valve.
Note: If you safety valve lifts at 10 bar instead of 9, then don’t try to set it down at the same time. Lower the pressure to 7 bar or something and then adjust the compression nut and then again raise the pressure to 9 bar. Otherwise you get all the wrong adjustment.
9) Once you are sure that it lifts at 9 bar, then
10) The distance between the bottom of the compression nut and the top of the safety valve cover bushes are measured by a scale of vernier caliper.
11) Then we have to make split ring of the same size and put. This kind of locks the compression nut.
12) Again fire the boiler and remove the gagging tool from the second safety valve and put it on the first safety valve.
13) Repeat the process with the second safety valve similar to the first one.
14) After both valves are set, they usually have some difference like 0.3 bar. This is not intentional and comes due to the fact that precise and similar adjust of both the valves is not same.
15) Put the easing gear on both valves and fire the boiler again. And finally see if both of them lifts at what pressure for final approval.
So this was all in the procedure which employs Boiler Safety Valve Setting.