Variable Spring Supports & Hangers

Overview

Variable Springs are used to support piping which is subject to thermal expansion and other factors that may cause the pipe support point to shift. The force of spring varies through the range of travel, hence the name “Variable Supports”. As the supported structure moves upward the force exerted by the spring decreases while the opposite occurs during downward movement.

Variable supports are typically installed where thermal movements cause the system’s position and dimensions to change; however, if the variability surpasses 25%, Rilco recommends our Constant Supports or the Rilco Cam Roller Constants.

All of the Rilco spring units are designed to meet or exceed the requirements of the ASME Code for Pressure Piping, ASME B31.1, B31.3, and MSS SP-58.

View our Variable & Constant Spring Catalog for complete specs.

Selecting the Correct Variable Spring

In order to manufacture a variable spring, some of the following data will need to be known:

Part No.
Size
Type
Operating load or hot load
Installed load or cold load
Movement and its direction

One of the first 5 conditions in the chart below must be met (condition 6 is used to obtain pricing only)

Condition	Known	Unknown
1	Part No., Size, Hot load, Movement & Direction	Cold load
2	Part No., Size, Cold load, Movement & Direction	Hot load
3	Hot load, Movement & Direction	Part No., Size, Cold load
4	Cold load, Movement & Direction	Part No., Size, Hot load
5	Hot load, Cold Load & Spring rate	Part No., Size & Movement
6	Figure, Size, Type	Hot load, Cold load, Movement & Spring rate

Information needed for Ordering

One of the conditions mentioned in the above chart (selecting the correct spring)
Preferred spring housing final coating/finish
Any parts that are not Rilco standard (Example: lifting lugs)

Spring Types

Drawing	Rilco Type	Description
	A	Hanger-Type Support: Design for use where headroom is unlimited. Top of spring housing is a rod which allows the spring to attach to a support.
	B	Single-Lug Hanger Type Support: Designed for use where headroom is limited. Top of spring housing has a single lug to accommodate a double-lug beam attachment from the top support.
	C	Hanger-Type Support: Designed for use where headroom is limited. Top of spring housing has double lugs to accommodate a single-lug attachment from the top support.
	D	Hanger-Type Support: Designed for use where variable spring hanger is positioned above supporting structure with spring adjustment made from the top.
	E	Hanger-Type Support: Designed for use when spring adjustment must be below the structure on which the spring housing is being supported.
	F	Base-Type Support: Designed for supporting piping from below.
	G	Hanger-Type Support: Designed for use where headroom is limited or where an obstruction prohibits the use of a single spring hanger.

Figure Numbers/Sizes and Grinnell Equivalents

Rilco		Grinnell Equivalent
Part Number	Size	Figure Number	Size
RVS-82	0 – 22	82	0 – 22
RVS-268	0 – 22	268	0 – 22
RVS-98	0 – 22	98	0 – 22
RVS-3X	0 – 22	Triple	0 – 22
RVS-4X	0 – 22	Quadruple	0 – 22

Load Table

Variable Spring Load Tables in English and Metric Units

SpringSize	Rod Size (in.)	Load (lb.)		Spring Rate (lb./in.)
SpringSize	Rod Size (in.)	Minimum	Maximum	RVS-82	RVS-268	RVS-98	RVS-3X	RVS-4X
0	1/2″	50	88	30	15	7	5	4
1		74	126	42	21	10	7	5
2		95	162	54	27	13	9	7
3		123	210	70	35	17	12	9
4		165	282	94	47	23	16	12
5		221	378	126	63	31	21	16
6	5/8″	294	504	168	84	42	28	21
7		392	672	224	112	56	37	28
8		525	900	300	150	75	50	38
9	3/4″	700	1200	400	200	100	67	50
10		910	1560	520	260	130	87	65
11		1190	2024	680	340	170	113	85
12	1″	1575	2700	900	450	225	150	113
13	1″	2100	3600	1200	600	300	200	150
14	1 1/4″	2800	4800	1600	800	400	267	200
15	1 1/4″	3780	6480	2160	1080	540	360	270
16	1 1/2″	5250	9000	3000	1500	750	500	375
17	1 3/4″	7000	12000	4000	2000	1000	667	500
18	2″	9320	15970	5320	2660	1330	887	665
19	2 1/4″	12380	21230	7080	3540	1770	1180	885
20	2 1/2″	16450	28200	9400	4700	2350	1567	1175
21	2 3/4″	21875	37500	12500	6250	3125	2083	1563
22	3″	29173	50010	16670	8335	4167	2778	2034

Finish

Finish or coating on the spring housing is dependent upon the environment in which the springs are installed.

Possible Finishes Include:

Black
Plated
Hot-dipped Galvanized

Specifications

Component	Rilco Standard?	Description/Comment
Coil	Yes	Neoprene or powder coated & designed per MSS-SP58
Travel stops	Yes	Hydrostatic & Upper stops are standard
Metal name plate	Yes	Stainless steel etched with client tag, Rilco part number, size, type hot load, cold load, spring rate & movement. Loads and movements available in imperial or metric unit.
Guided load column (Type F only)	No	Specify guided load column when required.
Lifting lugs	No	Recommended for spring weighing more than 100 lbs. or 45 kg.

Formulas and Calculations

pward movement	If cold load is greater than hot load
Downward movement	If hot load is greater than cold load
Movement	= (Cold load – Hot load) / Spring rate. If result > 0 then movement direction is up. Otherwise, it’s down.
Variability (% load change)	= (Movement x Spring rate) / Hot load x 100

Terminologies

Variable Spring Hanger & Support Terminologies