Expansion and Contraction Control Flashcards
What are the four types of movement that may be created by stress on or in the piping system?
A) axial movement due to pressure thrust
B) lateral movement
C) angular rotation
D) torque on piping and components
What type of pipeline movement occurs where all motion is in a straight line along the longitudinal axis of the pipe?
Axial movement
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?
Elastic properties
When installed in an above ground pipeway, why would the middle leg of a pipe in an expansion loop require a moment guide?
To prevent excessive bowing.
What type of expansion loop is used in horizontal pipe racks where the loop must be raised to clear adjacent piping?
Offset expansion loop
What may be created between the packing and the end of the hub in sleeve type expansion joints installed in the horizontal position?
A small water pocket
What governs the number of corrugations required in a bellows type expansion joint?
The amount of expansion to be absorbed
What expansion control device uses a combination of 2 hinged joints attached to a common ring in the center of the joint?
Gimbal expansion joints
What is the name for the device that would prevent a point on the piping for moving?
Anchor points
Why should vertical walls not be used for anchor points unless they have been engineered for this service?
Very poor resistance to horizontal thrust
Whose job is it to ensure that the anchor points required for the piping are strong enough to withstand the forces acting against them?
Structural engineer
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?
Thrust pad
What will occur as the ends of the pipe begin to push against the anchor points?
The compressive forces will cause the line to deflect
In which direction do point supported piping systems have a natural tendency to deflect between the supports?
Downward
In which direction will a run of pipe supported along its entire length, most often deflect?
Sideways
What are the 2 most critical factors to consider in determining the maximum distance between the anchors?
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
Anchors are required to hold against the pressure thrust inside the piping. What else must they be capable of holding against?
The forces created by friction between the pipe and the control system
Why would you install rollers under the pipe or pipe shoes?
To reduce the friction load imposed on the anchors
What would be used to prevent piping hung with long hanger rods from swaying?
Sway braces
If bellows joints create extra load against the anchors, why are they used?
Bellows joints and slip joints are used because they take up much less room, then pipe loops
Which types of joints impose the least amount of thrust against the anchors?
Ball joints, hinged joints, gimbal joints
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?
Bends at changes in direction
Why are carrier devices used in long runs of thin-wall or small diameter pipe or tubing?
To prevent excessive sag or deflection during operation
What type of expansion joint is used with rigid plastic piping materials such as PVC pipe?
Piston-type expansion joint
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?
Use the appropriate charts or tables
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?
Moment guide
What should be used to determine the lengths of the legs in an unequal spread expansion loop?
Tables or slide charts
What is the disadvantage of an offset expansion loop over a regular expansion loop?
Offset expansion loops put more stress on the piping as rotational torque
What types of post heat-treatment may be required for some materials when used for expansion loops?
Annealing or stress relieving
Why would hinged, gimbal, or ball type joints be chosen for use in a piping system?
They can handle large amounts of movement in a small space with minimum thrust of the anchors
When would an inline expansion joint be used in preference to a piping offset?
When the loop takes up too much room
If a bellows expansion joint does not have control rods, where should the first set of guides be placed?
Within 2’ of the bellows
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?
Install a hinge expansion joint in the horizontal piping
What needs to be determined before an expansion or contraction compensation device is installed in a system?
Direction and amount the pipe will move after installation
What should be done before anchoring the lines when the ambient temperature is radically different than the temperature range specified for installation?
Consult the piping engineer for the proper procedure to follow
What has to be done if a sleeve-type joint has been received fully compressed?
Pull the joint open mechanically to open the amount required
What should be done before removing the shipping bars from a bellows-type expansion joint?
Anchor and hydrotest the line at design installation temperatures
Formula for Expansion or Contraction
Length ×
Coefficient of Expansion ×
Temperature Change
