Ball Valve Seat Arrangement

A1) Consider the effect of not lapping the valves in the head of an internal combustion engine, thereby not forming a good seal, on the performance and efficiency of the engine.

Do you know what the term "lapping" means? If so, the statement in the spec. should be obvious. If not, Google is your friend.

And, it isn't how a dog drinks water.

Or running or dancing, although the concept is in there somehow

Some people here are incredibly unhelpful but Google would have helped. Lapping is typically a manual process (by hand) where you use a very fine grinding paste and a device that holds the two parts in the correct orientation and slowly grinds one against the other so that a perfect seal is achieved.

Some (most) people never bother to read the rules, either.

I won't bore you by posting the rest of the reasonable and typical rules.

" 14) Are there specific rules for posting?

Although you are free to post as you wish, as long as your post does not violate the CR4 Site Use Policy, we ask that you follow these guidelines when posting or commenting on CR4.

• Look for answers before you post. Check a search engine or two to see if you can find the answer to your question or a collection of useful links. If you can't, or if the answer you find is unclear, then that's a pretty good justification for asking the question on CR4. We don't want to stifle questions, but you're more likely to get a helpful response if you've done a little research on your own."

New members would do well to observe the casual banter that goes on here all the time.

Also note that many talented people (not including me) help to solve many complex, technical problems for those who come here asking legitimate questions.

Finally, in response to your good answer regarding lapping, I doubt that many valve seats are hand lapped these days.

In my youth, I did hand lap internal combustion engine valves.

Never lapped a ball valve.

I trust you will not be put by my response.

Its amazing!!! You people seem to have some kind of divine knowledge.

When and where did I say that I did not search in google and/or did not ask anyone and just posted in CR4?

Many question may just seem simple and straight forward to you experienced guys and native english speakers!!! But not every1 is same... To be frank, I din't know the meaning of word "Lapping", I am not a native english speaker.

Anyways.. Expected such replies from some people who usually reply the same way whatever you ask... But also hoped some helpful tips will come... Its a package deal you know... Ignore the rubbish and take what is good... Cheers...

Sorry.

The first response I got when using a search engine was, "Lapping is a machining process, in which two surfaces are rubbed together with an abrasive between them, by hand movement or by way of a machine."

Lapping - Wikipedia, the free encyclopedia

I didn't realize that you had such difficulty with the search.

This: 4

and this: #7

would seem to have answered your questions.

As you said, you get to decide which responses are good, or not. Just as you would have if you had used a search engine.

Cheers.

You must be a man!

Why you might ask? Because I am reminded of the old butter in the fridge problem:

Wife: Can you please get me the butter from the Fridge?

Husband (opens the Fridge and has a thourough look): There is no butter!

Wife: Yes there is!

Husband (while closing the fridge): No there is nothing in there.

Wife (now angry opens fridge): And what is that?

Husband: Oh thats butter. I was looking for the red label.

So you actuallu had a look, right?! As a none native speaker I understand the issue with technical terms and that it is not always easy to know what it means.

But put it that way: Do not wonder why nobody here understands that you could not find "Lapping" in a simple web search. The same way your wife will never understand that you could not see the butter!

You are on the losing end buddy!

1. What is the meaning of this statement found in ball valve specification "The ball and metal seat ring assembly shall be part matched by lapping".

Valve lapping is nothing but an operation used to make better contact between the ball and metal seat ring. This will prevent leakage between ball and seat.

Example for better understanding (Taken from an automobile valve repair section)
2. What is the meaning of Primary Metal Secondary Soft (PMSS) design? Is it that the metallic seat will be in direct contact with ball and a secondary soft seat is given in case of damage to primary seat? Or vice versa?

Soft seated valves are used for standard service. Metal seated valves are used for elevated temperature service and abrasive service

Metal seat
Flowserve
http://www.rma-armaturen.de/UserFiles/File/pdf/HKSF-W100%20E.pdf
http://www.engineeringtoolbox.com/control-valves-leakage-d_484.html