Valve Technology

What is the application? What kind of valves? Mounted in a pressure head? in the block? Why are the valves being repaired?

Did a shaft break bending the valves? Are the valves just leaking from build up?

Do the valves need adjusting from long term use? Did a valve spring break or is it leaking causing blow back?

WHEN IN DOUBT GET HAVE NEW VALVES, SPRINGS and lock caps installed. Cut new seats grid or cut for proper length.

Be careful what you tell a mechanic to do. He will allow you to be the boss and do what he is told or he can check for problems the might have caused the valve problem.

Mechanic have learned over the years to let the people paying the bills to make decisions. So be careful what you decide. Tell the mechanic you think you need a valve job or the shop boss. Then ask if there is anything else that should be checked. Don't act like you know it all let them do their work.

Generally valves are the easy part of repair job so the tech who does it will be checked by someone. Just ask them what they check for like spring tension, spring height, valve length, valve seat width, and material the valve is made of.

Silly me, I was thinking of Vacuum Valves, and was wondering how they were being refurbished... and trying to imagine a workman coming here and fixing them...

We don't use to buy refurbished valves. Repairing is a different thing, valves can leak though the packing or seat (resilient ones more easily) or even through the bonnet to body gasket. They need to be maintained (greased, etc).

The valve world is too wide for a simple answer. For complex ones we use to ask the valve manufacturer when possible. If this is not possible (some manufacturers disappear) for that valves we use only very qualified companies.

For common globe, gate, butterfly, check, etc valves there are more suppliers that can give you a good service.

Even in some cases, we don't repair the valve, we change the complete valve for economical reasons, as for example in small valves which are seat leaking and have a seal weld between body and bonnet. It's cheaper (and quicker) to replace the complete valve than to cur the lip seal, repair the seat, reweld the lip seal....

Best regards

Please confirm the material of every part first, is confirming the situation that each part is being damaged, it is a tedious job that one is repaired in the valve, is ok.

we have the problem regarding reparing of the ball valve, specially valve seat. to make the valve seat from teflon its very costly in kenya. can u please give another option material. can u please explain me what affects when we close the valve suddenly why we suppose to close it gradually. i want to explain my operators technically.

Plastic or metal ball valves?

What size?

What materials [fluid ] are in the pipe.

what temprature?

Teflon is used because it is slippery, impervious to many chemicals & can take eleveted tempratures.

Other plastics may work depending on the conditions

Quickly closing any valve can cause damage from increased pressure.

The larger the pipe the the greater the possibility of damage.

metal ball valve

4 inch

material is soap slurry

temperature is 80-100 degree celcious

please explain me how the larger the pipe more damages

I'll give it a shot.

The larger the pipe the more [force] energy is contained in the flow.

doubling the size of the pipe multiplies the volume times 4.

When you shut a valve quickly the energy in the flow bounces back, momentarily raising the pressure. The energy has to go some where!

i have one steam header which has 17 bar pressure and four lines are connected to it one of the line having pn 16 valve

what is this pn

if it means 16 bar what capacity of steam valve i have to put there

Here's some info:

http://www.engineeringtoolbox.com/temperature-pressure-ratings-valves-d_1182.html The chart shows bar having a 1:1 relationship to PN#

To follow up on the valve seats.

Because of the temperature you probably have to use teflon for the valve seats

http://www.boedeker.com/mtable.htm