seals gaskets and packing

Question 1

What is the difference between static and dynamic seals

Answer 1

Static seals: used where there is little or no movement between contacting surfaces

dynamic seals: used to seal moving surfaces

Question 2

How to tighten a rectangular flange

Answer 2

Tighten from the inside out using a spiral pattern

Question 3

Explain the three step method for achieving final torque when torqueing a series of fasteners

Answer 3

If the final torque is 60 foot lbs than torque in at least 20 ft lb increments. So you would tighten all at 20 then 40 and finally 60

Question 4

Name the two typical causes of gasket failure

Answer 4

Installation mistake
damaged gasket
contaminants

Question 5

The o ring is considered the most common type of

Answer 5

elastomer seal

elastomeric seals are seals made from a flexible polymer

Question 6

What are the most common causes of o ring failure

Answer 6

installation mistake
damaged ring or grooves
poorly prepared surfaces
incorrect material

Question 7

Three main parts of simple stuffing box

Answer 7

packing chamber: the stationary housing for packing rings

Packing rings: made of soft compressible matieral

The gland follower:(stuffing gland): used to compress packing rings`

Question 8

What is a lantern ring

Answer 8

A ring installed in the middle of the packing and is a specially designed spacer(usually made of metal) that allows the introduction of an outside fluid

Question 9

What is automatic packing

Answer 9

A type of molded packing where internal air or fluid pressure forces the lips of the seal to press against some hard surface. It is the internal pressure that does the sealing and not the outside pressure from tightening

Question 10

List three points where a mechanical seal must seal

Answer 10

1. The static seal between the housing and stationary part of seal
2. A static seal between shaft and rotating part of mechanical seal
3. a Dynamic seal between the rotating surface and the stationary seal face

Question 11

Name 4 advantages of mechanical seals

Answer 11

zero leakage
handle higher pressure
better at chemical sealing
little to no shaft wear
less maintenance 
no adjusting 
less friction
more efficient

Question 12

What is a labryinth seal

Answer 12

Are noncontacting seals that have a series of small chambers separated by ribbed protuberances with a very small shaft clearance

each rib creates a pressure drop so back pressure is what keeps lubricant sealed