Hand wheel of gate valve get broken 1

[amrishmd]

hi there, I am glad to be a member of this valuable forums

actually I have been faced an issue with gate valve hand wheel let me tell you about it
this is the second time hand wheel broken, in first time we recommended to re-routing the line according to the isometric drawing because it was in non conformity condition with the drawing . but after 3 months the hand wheel get broken again. we say that it's due to improper of using by applying heavy force from operator or improper selection of material. all things as per drawing but now they assigned me to do study and find out solution to prevent the hand wheel get broken again. I am looking for experts in elaborating to identify the root cause for it in urgent basis. the material for body is A 105 and for hand wheel is carbon steel.

 

[pennpiper]

More information could help.

What is the line size?
What is the pressure class (Class 150, Class 300, Class 1500, etc.)?
What is the commodity?
What was the action that accompanied the break (normal opening/closing or impact by crane)?
Can you attach a photo of the installation?


Sometimes its possible to do all the right things and still get bad results

 

[amrishmd]

dear Mr. pennpiper

thanks for responding

the line size is 1 inch and the medium is hot water
gate valve class is CL 800 : (Gate Valve SW, CL800, A105 13CR trim HF VAS-JD1 W (CG4A02)
line operating pressure and Temp P=39 bar and T=145 C

and please find attached photo for your reference

 

[amrishmd]

the broken part is a stem not the hand wheel please find attached gate valve drawing

 

[gerhardl]

When any mechanical part is broken, it is clarly result of an excessive force. My first guess is the same as yours: faulty operation. As a more 'technical analysis' following comment:

Your drawing and picture shows that the stem is broken as a break starting from the bottom of a thread. The break is following the thread grove around the stem, but is else straight across the stem. The picture is not sharp or detailed enough to show the structure of the broken metal. It is not possible from the picture to tell if the break is at a position with closing member of the valve (gate) in closed or open position.

Preliminary conclusion: excessive force, by turning the wheel with force past the end position of the gate, probably (but not necessarily) with stem/gate in upper position, overstretching the stem. It is possible that he break could be initiated (systemeatic since two stems broken?) by machining or material fault, underdimensioning or wrong type of stem material.

Possible checkpoints: Visiual inspection of stem and break surface, operational inspection and interviews at site, microscopic inspection of break, inspection and test of stem material. Inspection of valve to see if valve closes and opens ok (no excessive force necessary).

Possible corrections: New correct valve, operational instruction and inspection at site, valve equpped with limit switches, and/or gear operator with limit and torque switches.

 

[pennpiper]

gehardl,
My thoughts exactly.

Sometimes its possible to do all the right things and still get bad results

 

[LittleInch]

You need to talk to the operators in a non blame fashion to find out what was actually going on.

Did any of them stand on the hand wheel to get somewhere else / look at something else?
Is the hand wheel the right size? - looks a bit bigger than 100mm to me, but maybe that's the photo
Did any of them tighten up the glands too much?
Was the valve passing when turned off just b hand - This is my probable cause as most operators know you can apply more sealing force to a gate valve by adding more torque to the valve.
How many time was it greased?
How many times was it opened or closed? Alternatively it was closed for a long time and the gate became wedged against the set too much.
Is the thread depth too deep? Thread looks quite sharp edged internally, but a higher resolution picture / close up would be nice
Is the material what it says it is?
what did they use to tighten the valve?
Consider a ball valve - Sealing is sometimes not as good, but once you've turned it 1/4 turn, there is no more point in applying more pressure, it won't seal any better.

Look at use of the right grease and lubricants. At 145C a lot of them will simply evaporate and loose effectiveness if not suitable for the temperature.

Let us know what you found out.


Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[amrishmd]

thanks to all participants

more photo in order to accrue recommendation

 

[amrishmd]

more photo in order to accrue recommendation-2

 

[amrishmd]

tighten by using a wrench-

 

[LittleInch]

you've answered you own question - the stem looked like it had had a big pair of stilsons on it and if that was what they were using to close it the hand wheel has become squeezed by the wrench not being applied exactly flat.

Clearly ther eis something wrong with this valve operation if the handwheel won't close it. My suspect is lubrication not suitable for the temperature, gate becoming stuck and also difficulty sealing. You need to look at alternative valves - plugs maybe or slab gates / expanding gates or just accept that you will replace it every tree months...

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.