Constant hanger terminology
Constant spring hangers are spring-based pipe supports designed to accommodate vertical movement while maintaining an approximately constant supporting load. Engineering catalogues also use constant support hangers and constant effort supports. This page covers the suspended MA series; the base-mounted series and lever-type hangers have separate configurations. Similar terminology does not establish dimensional or performance interchangeability.
Construction — main & auxiliary spring mechanism
The MA-Series replaces the conventional lever-and-cam linkage with a main vertical spring working against a matched auxiliary spring group in a rigid housing, supplied as hanger-suspended (this page) or base-mounted constant supports, with load adjustment and travel scale. Each unit is bench-tested and locked at the cold position before dispatch.
- Load deviation ≤3% across the full travel range, verified on the load–travel test bench (MSS SP-58 limit: 6%)
- Dual-axis behaviour — vertical constant support plus lateral damping from the auxiliary spring group
- Travel up to 300 mm and above for special cases
- Adjustment allowance typically ±10% of design load
- Hydrotest stops and transport locks fitted as standard
How it works — and why it beats the linkage design
In a lever-linkage constant hanger (the conventional lever-and-cam layout most suppliers build), constancy depends on cam geometry approximating a curve — the supporting force is near-constant, and wear at the pivots erodes even that. The MA mechanism takes a different route: the auxiliary springs generate a force component that mirrors the main spring's deviation, and the superposition of the two is constant by mathematics, not by approximation.
The diagram reads simply: over the full travel the main spring's force climbs linearly, the auxiliary group's vertical component falls by the same law, and their sum stays flat. On the test bench that translates to a measured deviation within 3% — and because the auxiliary springs also react sideways loads, the unit damps lateral vibration that a single-axis design passes straight into the pipe.
We build the conventional pattern too — see our lever-type constant hangers for general service where the standard 6% is sufficient.
Typical Specification
| Item | Range / Detail |
|---|---|
| Design practice | MSS SP-58; project specs on request |
| Load range | ~0.5 kN to 200+ kN per support |
| Travel | 25–300 mm typical |
| Load deviation | ≤3% bench-verified (MSS SP-58 limit: 6%) |
| Lateral damping | Auxiliary spring group, dual-axis |
| Testing | Load-travel bench test report per unit |
Where they are used
Main steam and hot reheat lines in power plants, high-temperature process lines, and any location where a variable hanger's load change would overload the pipe or connected equipment.
Engineering resources
- Constant support RFQ checklist: load, travel, arrangement and drawings
- Variable vs constant spring hangers: which one does your line need?
- How to select a variable spring hanger — worked example
- MSS SP-58 hanger types A–G, explained
- How to read a hanger schedule, column by column
- Spring hanger installation guide — travel stops, hydrotest & commissioning
Frequently asked questions
What information do you need to quote a constant force hanger?
Hot load (operating load), total vertical travel with direction, pipe size and temperature, and whether the unit is hanger-suspended or base-mounted. A hanger schedule or marked-up stress isometric is ideal — we size each support and return a data sheet per tag.
Do you design to MSS SP-58?
Yes. MA-Series constant hangers follow MSS SP-58 design practice and hold load deviation within 3% across the full travel range, verified on the test bench — well inside the 6% the standard allows. Hanger-suspended and base-mounted arrangements are available, and we work to project specifications on request.
What surface finishes are available?
Primer finish as standard on the welded steel frame, with epoxy systems or hot-dip galvanizing to project specification — HDG is common for GCC coastal and outdoor plant environments.
Do you supply complete assemblies, and is there a minimum order?
Each tag can be delivered as a complete assembly — constant support unit plus rods, clamps and building attachments. Constant hangers are engineered items quoted per project, so any minimum order considerations are confirmed at quotation.
What documentation is provided with an order?
A load-travel bench test report per unit, a data sheet per support tag, dimensional and inspection reports, and material certificates on request, plus export packing documents. Units ship with hydrotest stops and transport locks fitted.