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PSV butt weld inlet #2500 - Nozzle Seat Removal 2
- Thread starter Adnan.B
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The Obturator
Mechanical
Difficult these things. The answer is generally No. The OEM may have a device called a Reseating Machine that bolts onto the body where the bonnet is located. The cutting tool has the nozzle face profile. The machine is usually hand operated and will finish cut a new profile, provided the material on the nozzle has not already had it's limit exceeded with previous maintenance. Then just finish lap and its done. You may be able to hire such a machine.
*** Per ISO-4126, the generic term 'Safety Valve' is used regardless of application or design ***
*** 'Pressure-relief Valve' is the equivalent ASME/API term ***
*** Per ISO-4126, the generic term 'Safety Valve' is used regardless of application or design ***
*** 'Pressure-relief Valve' is the equivalent ASME/API term ***
- Thread starter
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The Obturator
Mechanical
Don't confuse the nozzle threading as being used to screw into the body - it may be just the nozzle ring threads on the nozzle. It's possible too that a special was made by the OEM. Also someone could have machined out the weld securing the nozzle and gave up. It's best if you take the serial number to the OEM or their local rep to identify the valve for you. The reseating machine I advised on is featured in the 1700 repair manual which I attach here. Page 28 - note nozzle is referred to as a bush. Hope that was useful.
*** Per ISO-4126, the generic term 'Safety Valve' is used regardless of application or design ***
*** 'Pressure-relief Valve' is the equivalent ASME/API term ***
*** Per ISO-4126, the generic term 'Safety Valve' is used regardless of application or design ***
*** 'Pressure-relief Valve' is the equivalent ASME/API term ***
- Thread starter
- #6
![[2thumbsup]](/data/assets/smilies/2thumbsup.gif "[2thumbsup] [2thumbsup]")
The Obturator
Mechanical
Some end users have in past simply mounted the body on a lathe chuck, centred up the nozzle and machined from there. Just check the integrity of the weld afterwards like a hydro. In cases where there is not enough metal to properly machine a seat to re-machining dimensions shown in OEM manuals, some 'outfits' have welded a layer or two onto the damaged seat and dressed the seat from there......problem is later when the valve is installed and the steam heat is up, the 2 differing materials from original seat and weld material expand at different rates and the seat gets distorted and then the leaks start and get worse. This why some OEMS don't recommend stellited seats. Just thought I'd drop that in.
*** Per ISO-4126, the generic term 'Safety Valve' is used regardless of application or design ***
*** 'Pressure-relief Valve' is the equivalent ASME/API term ***
*** Per ISO-4126, the generic term 'Safety Valve' is used regardless of application or design ***
*** 'Pressure-relief Valve' is the equivalent ASME/API term ***
- Thread starter
- #8
The Obturator
Mechanical
It's might not be stellite but a hardened alloy rather than the usual stainless steel at that pressure. The point was, different materials = different expansions. I would check if you have enough material left if you can machine a proper seat.
*** Per ISO-4126, the generic term 'Safety Valve' is used regardless of application or design ***
*** 'Pressure-relief Valve' is the equivalent ASME/API term ***
*** Per ISO-4126, the generic term 'Safety Valve' is used regardless of application or design ***
*** 'Pressure-relief Valve' is the equivalent ASME/API term ***
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