Static seals

Question 1

A static seal is a seal between:

Answer 1

two stationary parts

Question 2

Seals which prevent any fluid from leaking from one side of a system to another are called:

Answer 2

positive seals

Question 3

Seals which control the amount of leakage are called:

Answer 3

non-positive seals

Question 4

Static seals seal two surfaces which have little or no movement. All static seals are ____ seals

Answer 4

positive

Question 5

Two ways of sealing two mating surfaces without additional materials is: (2)

Answer 5

• tapered fit

- interference fit

Question 6

_____ are installed at a joint between stationary surfaces to seal against a pressure load, seal against leakage, and to control position.

Answer 6

Gaskets

Question 7

Gaskets are sealed by:

Answer 7

Force of compression exerted by the bolts

Note: Must be greater than internal pressure, hydrostatic end force (which pushes the joints apart)

Question 8

When using gaskets to seal housings, it’s important that the original gasket thickness is known and the same thickness replaced. This avoids changing:

Answer 8

internal clearance

Question 9

Always consider gasket ___ when replacing gaskets in an axially split pump with wearing rings

Answer 9

thickness

Question 10

What are these styles of? flat (full) face, raised face (ring), tongue and groove, spigot and recess?

Answer 10

gasket joints

Surfaces must be parallel and regular in finish

Question 11

Gasket material is designed to conform to machined surfaces or to ___ slightly to fill small irregularities.

Answer 11

flow

Question 12

The compression of a gasket is greatest at the:

Answer 12

bolt locations

Closer the bolts, more even the compression. Thinner the material, the more bolts you need for even compression

Question 13

Gasket material should: (3)

Answer 13

• Withstand the bolt load
• Withstand temperature and pressure
• be compatible with the product

Question 14

This non metallic gasket material is inexpensive. Often impregnated with fillers such as wax and seals well against water, oil, petroleum fuel. Temperature limit is 120°C

Answer 14

Paper

Question 15

This non metallic gasket material is used in low pressure applications. Can be impregnated with an elastomer. Seals well against water, oil, and solvent. Useable between -30°C and 150°C

Answer 15

Cork

Question 16

This non metallic gasket material has excellent mechanical properties and resists water and air. Temperature limit is 121°C

Answer 16

Natural rubber

Question 17

This non metallic gasket material includes a variety of materials such as buna-s, buna-n, butyl, neoprene, nitrile, viton, silicone.

Answer 17

Synthetic rubber

Question 18

This non metallic gasket material is used today only for special applications like high temperatures and steam turbines

Answer 18

Asbestos

Question 19

This non metallic, plastic gasket material resists heat, oil and oxidization, but does not perform well at low temperatures. Temperature limit of 232°C

Answer 19

Acrylic

Question 20

This non metallic, plastic gasket material is nearly chemically inert, performs well in extremely low temperatures. -190°C to 250°C

Answer 20

Teflon

Question 21

Gaskets are often coloured to show:

Answer 21

thickness

Question 22

Metallic gaskets are usually used in what applications?

Answer 22

high temperature high pressure

Question 23

Metallic gaskets can be solid or a:

Answer 23

composite of several materials

Question 24

Flat, V or U, rectangular, triangular, octagonal, round, oval, spiral-wound, corrugated, embossed, jacketed with a filler core, metallic inner ring and non metallic outer ring are all examples of what?

Answer 24

Metallic gasket cross sections

Question 25

Metallic gaskets seal by the:

Answer 25

flow or malleability of the gasket when compressed by bolts. Smoother the surface finish, the better the seal

Question 26

The circular gasket can have two styles: (2)

Answer 26

- Ring style | - Full face

Question 27

The ring style gasket is preferred because: (2)

Answer 27

- Takes less time to make it | - Easier to install

Question 28

_____ gaskets are normally supplied pre stamped and formed for a particular application

Answer 28

metallic gaskets

Question 29

What two methods can be used to draw out a seal? (2)

Answer 29

- Take measurements and draw from those | - hold the gasket material against the face and transfer it with blueing or by drawing

Question 30

Protect the end of a gasket hole punch with a:

Answer 30

block of wood

Question 31

What three things should you do before installing a new gasket? (3)

Answer 31

- Remove all of the old gasket - Check faces for irregularities, smooth if necessary - Smear a light film of lube on the contact surfaces

Question 32

An o ring can be a static or a dynamic seal, and is usually made of:

Answer 32

synthetic rubber

Question 33

An O ring usually does not make a difference to the _______ of machine parts

Answer 33

relative position Note: the joint is designed so the correct compression of the o ring happens when the two machined surfaces are in contact

Question 34

The material for a chosen o ring is chosen to: (2)

Answer 34

- resist chemical - suit temperature Note: O rings not made of synthetic rubber are marked by the manufacturer

Question 35

Metallic O rings are used where extreme conditions of:

Answer 35

temperature, pressure, corrosion exist

Question 36

Multi lobed, square and rectangular cross section "o rings" are often used as gaskets in:

Answer 36

hydraulic equipment Note: made from the same materials as standard O rings

Question 37

A _____ is a gasket forming or sealing compound used in zero to low pressure applications. Found in tape, paste, or liquid form.

Answer 37

sealant Usually used with a gasket to fill minor depressions in sealing surfaces caused by corrosion

Question 38

______ sealants are mastic (resit) materials which are soft and adhesive. Usually contain plasticizer which allows them to remain soft.

Answer 38

non hardening sealants

Question 39

_____ sealants are available in a variety of materials such as butyl, acrylic, silicone and polyurethane. These materials contain curing or setting agents which allow them to remain flexible

Answer 39

hardening-flexible sealants

Question 40

_____ sealants are based on epoxies, polyesters, acrylics, polyamides, or polyvinyl acetates (PVA). Cure to a rigid state. Tend to crack and result in joints that are difficult to remove. Sometimes used to join as well as seal.

Answer 40

Hardening-rigid sealants

Question 41

____ are a type of sealant. Available in a variety of shapes for different applications, such as edge, sandwich, lap sealing

Answer 41

tapes