VARIABLE SPRING HANGER SELECTION
SPRING CAN SERIES, SIZE AND TYPE SELECTION
Use the following information to select the Spring Can Series (Fig 268, 82, 98, Triple, or Quad) and Spring Can Size (000 through 22) that best fit the application. The Spring Can Size determines the loads that can be supported, or the load range. The series, or figure number of the Variable Spring Hanger specifies the amount of vertical travel possible. As a starting point for series selection, use Fig. 82 for up to 1⁄2″ of movement, up to 1″ use Fig. B-268, up to 2″ use Fig. 98, up to 3″ use a Triple, up to 4″ use a Quadruple. The type of installation the application calls for will specify the Type of Spring Can (Type A, B, C, D, E, F, or G) that will be required.
How to use hanger selection table: In order to choose a proper size hanger, it is necessary to know the actual load which the spring is to support and the amount and direction of the pipe line movement from the cold to the hot position. Find the actual load of the pipe in the load table. As it is desirable to support the actual weight of the pipe when the line is hot, the actual load is the hot load. To determine the cold load, read the spring scale, up or down, for the amount of expected movement. The chart must be read opposite from the direction of the pipe’s movement. The load arrived at is the cold load. If the cold load falls outside of the working load range of the hanger selected, relocate the actual or hot load in the adjacent column and find the cold load. When the hot and cold loads are both within the working range of a hanger, the size number of that hanger will be found at the top of the column.
Should it be impossible to select a hanger in a particular series such that both loads occur within the working range, consideration should be given to a variable spring hanger with a wider working range or a constant support hanger. The cold load is calculated by adding (for up movement) or subtracting (for down movement) the product of spring rate times movement to or from the hot load.
Cold load = (hot load) ± (movement) x (spring rate) A key criteria in selecting the size and series of a variable spring is a factor known as variability. This is a measurement of the percentage change in supporting force between the hot and cold positions of a spring and is calculated from the formula:
Variability = (Movement) x (Spring Rate) / (Hot Load) If an allowable variability is not specified, good practice would be to use 25% as recommended by MSS-SP-58.
General rule for series selection use Fig. 82 for up to 1⁄2″ of movement, up to 1″ use Fig. B-268, up to 2″ use Fig. 98, up to 3″ use a Triple, up to 4″ use a Quadruple. Double check to assure desired variability is achieved.
The document below will assist the buyer in gathering the necessary information in order to receive an accurate quote.
Note: All material included on this page is informational only, and should not be used as one’s sole source for design purposes. STS Industrial, Inc. and its affiliates do not guarantee the accuracy of the information on this site, and retain no liability for the use or misuse of the information contained on this site.
Sources: Anvil International Pipe Hangers and Supports, Carpenter and Paterson Pipe Support Hardware