Expansion and Contraction Control

Question 1

What are the four types of movement that may be created by stress on or in the piping system?

Answer 1

A) axial movement due to pressure thrust
B) lateral movement
C) angular rotation
D) torque on piping and components

Question 2

What type of pipeline movement occurs where all motion is in a straight line along the longitudinal axis of the pipe?

Answer 2

Axial movement

Question 3

Which property of materials will allow a certain amount of flexure with the application of a small amount of force without permanently distorting the material?

Answer 3

Elastic properties

Question 4

When installed in an above ground pipeway, why would the middle leg of a pipe in an expansion loop require a moment guide?

Answer 4

To prevent excessive bowing.

Question 5

What type of expansion loop is used in horizontal pipe racks where the loop must be raised to clear adjacent piping?

Answer 5

Offset expansion loop

Question 6

What may be created between the packing and the end of the hub in sleeve type expansion joints installed in the horizontal position?

Answer 6

A small water pocket

Question 7

What governs the number of corrugations required in a bellows type expansion joint?

Answer 7

The amount of expansion to be absorbed

Question 8

What expansion control device uses a combination of 2 hinged joints attached to a common ring in the center of the joint?

Answer 8

Gimbal expansion joints

Question 9

What is the name for the device that would prevent a point on the piping for moving?

Answer 9

Anchor points

Question 10

Why should vertical walls not be used for anchor points unless they have been engineered for this service?

Answer 10

Very poor resistance to horizontal thrust

Question 11

Whose job is it to ensure that the anchor points required for the piping are strong enough to withstand the forces acting against them?

Answer 11

Structural engineer

Question 12

What may need to be fused onto a thin wall pipe to provide a strong enough support for an anchor on the run of the pipe?

Answer 12

Thrust pad

Question 13

What will occur as the ends of the pipe begin to push against the anchor points?

Answer 13

The compressive forces will cause the line to deflect

Question 14

In which direction do point supported piping systems have a natural tendency to deflect between the supports?

Answer 14

Downward

Question 15

In which direction will a run of pipe supported along its entire length, most often deflect?

Answer 15

Sideways

Question 16

What are the 2 most critical factors to consider in determining the maximum distance between the anchors?

Answer 16

A) The amount of movement the expansion control device is able to handle
B) The total forces the anchor points are capable of with standing

Question 17

Anchors are required to hold against the pressure thrust inside the piping. What else must they be capable of holding against?

Answer 17

The forces created by friction between the pipe and the control system

Question 18

Why would you install rollers under the pipe or pipe shoes?

Answer 18

To reduce the friction load imposed on the anchors

Question 19

What would be used to prevent piping hung with long hanger rods from swaying?

Answer 19

Sway braces

Question 20

If bellows joints create extra load against the anchors, why are they used?

Answer 20

Bellows joints and slip joints are used because they take up much less room, then pipe loops

Question 21

Which types of joints impose the least amount of thrust against the anchors?

Answer 21

Ball joints, hinged joints, gimbal joints

Question 22

What is used with tubing to take care of expansion and contraction of the lines without imposing excessive stress against the equipment or anchor points?

Answer 22

Bends at changes in direction

Question 23

Why are carrier devices used in long runs of thin-wall or small diameter pipe or tubing?

Answer 23

To prevent excessive sag or deflection during operation

Question 24

What type of expansion joint is used with rigid plastic piping materials such as PVC pipe?

Answer 24

Piston-type expansion joint

Question 25

How can you ensure that the thrust required to flex the pipe offset is not excessive and that the amount of flex in the pipe does not exceed the elastic limits of the pipe material?

Answer 25

Use the appropriate charts or tables

Question 26

What type of guide is designed to act as an anchor against side thrust as well as to maintain the axial alignment of the pipe?

Answer 26

Moment guide

Question 27

What should be used to determine the lengths of the legs in an unequal spread expansion loop?

Answer 27

Tables or slide charts

Question 28

What is the disadvantage of an offset expansion loop over a regular expansion loop?

Answer 28

Offset expansion loops put more stress on the piping as rotational torque

Question 29

What types of post heat-treatment may be required for some materials when used for expansion loops?

Answer 29

Annealing or stress relieving

Question 30

Why would hinged, gimbal, or ball type joints be chosen for use in a piping system?

Answer 30

They can handle large amounts of movement in a small space with minimum thrust of the anchors

Question 31

When would an inline expansion joint be used in preference to a piping offset?

Answer 31

When the loop takes up too much room

Question 32

If a bellows expansion joint does not have control rods, where should the first set of guides be placed?

Answer 32

Within 2’ of the bellows

Question 33

Gimbal joints are used in a pair to absorb the thermal expansion from the 2 horizontal piping legs. What should be done if there is expected to be a considerable amount of movement in the vertical leg?

Answer 33

Install a hinge expansion joint in the horizontal piping

Question 34

What needs to be determined before an expansion or contraction compensation device is installed in a system?

Answer 34

Direction and amount the pipe will move after installation

Question 35

What should be done before anchoring the lines when the ambient temperature is radically different than the temperature range specified for installation?

Answer 35

Consult the piping engineer for the proper procedure to follow

Question 36

What has to be done if a sleeve-type joint has been received fully compressed?

Answer 36

Pull the joint open mechanically to open the amount required

Question 37

What should be done before removing the shipping bars from a bellows-type expansion joint?

Answer 37

Anchor and hydrotest the line at design installation temperatures

Question 38

Formula for Expansion or Contraction

Answer 38

Length ×
Coefficient of Expansion ×
Temperature Change