EN 12845 Pipe Supports and Hanger Spacing

The invisible detail holding up the sprinkler network: what spacing, what anchor, what clamp.

On an acceptance walk at a logistics warehouse, looking up, we found a DN100 distribution main hung between two steel trusses over a 4.5 m span from a single M10 threaded rod. Water-filled, the pipe masses about 13 kg per metre; the sag was visible to the naked eye. EN 12845 sets a maximum of 4 m for steel pipe; this project had 4.5 m and the exception condition — two independent supports, or a hanger 50 % stronger — had not been met. Pipe support is the one detail skipped because nobody looks at it, and the one that can bring the whole installation down the night it is charged with water.

The basic rule

The pipe support section has three parts: general principles, spacing and position, and design parameters. First the principles:

• Supports are fixed directly to the building, and where necessary to machinery, storage racking or another structure. No other service — ventilation, cable tray, lighting — may be hung from a sprinkler hanger.
• Hangers must be of the adjustable type, so load is distributed evenly rather than concentrated at one overloaded point.
• The clamp must fully encircle the pipe and must not be welded to the pipe or a fitting.
• Pipe above 50 mm may not be hung from profiled metal decking or aerated concrete; a load-bearing concrete or steel structure is required.
• No support component may be of combustible material, and nails may not be used.
• On copper pipe, an electrically insulating liner goes inside the clamp to prevent galvanic corrosion.

Hanger spacing — a one-line rule, not a table

EN 12845 does not give a row-by-row table by diameter the way NFPA 13 does. It sets a single rule:

• Steel pipe: maximum 4 m spacing.
• Copper pipe: maximum 2 m spacing.
• Pipe above 50 mm: spacing may be increased by 50 % — 6 m for steel, 3 m for copper — provided one of two conditions is met:
  • Two independent supports fixed directly to the structure, or
  • A single support capable of carrying 50 % more than the tabulated load capacity.

In practice this summary works:

Pipe	DN	Standard spacing	With the 50 % exception
Steel	≤ 50 mm (DN25–DN50)	4.0 m	—
Steel	DN65–DN100	4.0 m	6.0 m
Steel	DN125–DN200	4.0 m	6.0 m
Copper	≤ 50 mm	2.0 m	—
Copper	> 50 mm	2.0 m	3.0 m

The standard does not state why copper needs closer supports. Engineering comment: copper's modulus of elasticity is markedly lower than steel's, so it deflects more over the same span and load.

Extra rules for mechanically jointed pipe

Mechanical joints such as grooved couplings are common on steel pipe, and the standard adds two conditions for mechanical joints:

• At least one support within 1 m of every mechanical joint.
• At least one support on every pipe length — a length with no support between two couplings is not acceptable.

Grooved pipe is less rigid between lengths than welded pipe; with no hanger, a turning moment develops at the coupling and the gasket leaks. So the 6 m exception is rarely applied on a grooved system — staying at 4 m is the safe practice.

Terminal sprinklers and the last support

An overlooked part of the clause is the sprinkler-to-support distance:

• On DN25 pipe: no more than 0.9 m from the end sprinkler to the last support.
• Above DN25: no more than 1.2 m.
• On upright sprinklers: at least 0.15 m between support and sprinkler. Closer than that, the hanger clamp obstructs the deflector pattern.

Additional support for vertical pipe

Vertical pipes must be supported as well as horizontal runs. Two limits apply:

• Additional support for vertical pipes longer than 2 m.
• Additional support for vertical pipes more than 1 m long feeding single sprinklers.

Low-level pipes at risk of forklift impact are separately supported; two exceptions apply — horizontal pipes less than 0.45 m long and drop or rise pipes less than 0.6 m long, each feeding an individual sprinkler, are exempt.

Design: hanger capacity and anchor size

The load capacity, cross-sectional area and anchor embedment of hanger components come from a table:

Nominal pipe diameter	Min. load capacity (20 °C)	Min. threaded section	Min. anchor embedment (concrete)
d ≤ 50 mm	200 kg	30 mm² (M8)	30 mm
50 < d ≤ 100 mm	350 kg	50 mm² (M10)	40 mm
100 < d ≤ 150 mm	500 kg	70 mm² (M12)	40 mm
150 < d ≤ 200 mm	850 kg	125 mm² (M16)	50 mm

Three notes are critical:

1. Load capacity must not fall by more than 25 % when the material is heated to 200 °C — so the hanger does not sag during a fire.
2. The threaded rod section must meet the values above after the thread is cut. M10 is nominally 78 mm² but 52 mm² at the thread root — very close to the limit.
3. The embedment depths are for concrete; in aerated or lightweight concrete and in brick, the manufacturer's table differs and usually requires 1.5 to 2 times the depth.

A second table gives minimum flat bar and clamp dimensions:

Pipe diameter	Flat bar (galvanised)	Flat bar (black)	Clamp (galvanised)	Clamp (black)
d ≤ 50 mm	2.5 mm	3.0 mm	25 × 1.5 mm	25 × 3.0 mm
50 < d ≤ 200 mm	2.5 mm	3.0 mm	25 × 2.5 mm	25 × 3.0 mm

Galvanised material may be thinner because the corrosion allowance has been removed; black or ungalvanised material loses section over time and so is required thicker at the start. In humid ceiling voids — kitchens, wet areas — ungalvanised steel hangers are normally rusty within five years; stainless hangers should be specified around pools, laundries and near-freezing stores.

Fire resistance and materials

No support component may be combustible. That effectively rules out plastic anchors, timber packers and nylon ties. In a fire, flame melts the plastic anchors first, the hanger drops, the pipe breaks and the system is out of service. Field practice:

• Galvanised steel threaded rod with a galvanised clamp in dry areas.
• 304 stainless in humid, chlorinated or external locations.
• Concrete anchors: steel expansion anchors. Plastic-sleeved anchors are not accepted on sprinkler work.
• Steel beam connections: beam clamps.

Seismic bracing: A2:2026 refers to EN 12845-3

For seismic bracing, TS EN 12845+A2:2026 Clause 13.1 gives the following recommendation: for areas at risk of earthquakes according to EN 12845-3, it is recommended to apply the requirements given in EN 12845-3 for the sprinkler system; the note explains that this ensures the system sways with the building, preventing leaks, pipe breaks and consequential damage. In Turkish seismic zones, leaving a sprinkler network on vertical hangers alone conflicts with the seismic bracing requirement of BYKHY Article 96(6). What is done in practice:

• Sway bracing to NFPA 13 principles on distribution mains (DN65 and above).
• Four-way bracing on risers; on horizontal pipe, lateral braces at no more than 12.2 m (40 ft) and longitudinal braces at no more than 24.4 m (80 ft) centres (NFPA 13-2025 18.5.5 and 18.5.6).
• Restraint of branch lines to NFPA 13-2025 Section 18.6, with spacing by seismic coefficient from Table 18.6.4.
• FM Global DS 2-8 (2.2.1.1) requires four-way bracing on risers regardless of size and lateral sway bracing on branch lines of 65 mm (2½ in.) and larger.

In Turkey the basic requirements are set by BYKHY Article 96(6). Because Article 5(2) gives precedence to Turkish standards, then European standards, and only then to other internationally recognised standards, EN 12845-3 should be consulted first for seismic bracing; NFPA 13 or FM Global DS 2-8 fill only what it does not cover.

A field error: unhung pipe inside a plasterboard ceiling

In a shopping centre being converted into a hotel, a DN50 sprinkler branch running inside the plasterboard suspended ceiling had been fixed to the ceiling profiles with plastic clips. There was no structural hanger at all. When the suspended ceiling collapsed in an earthquake, the pipe went down with it and water ran for 40 minutes until the main valve was shut. Two causes:

1. The pipe was invisible inside the ceiling, so site supervision could not check it.
2. A plasterboard profile is not a "structure" in EN 12845 terms and cannot carry sprinkler pipe. A ceiling profile does not have 200 kg of load capacity.

The correct arrangement: an M10 anchor into the concrete above, threaded rod and clamp; the ceiling profile carries only the sprinkler escutcheon.

Comparison with NFPA 13 hanger spacing

NFPA 13-2025 Table 17.4.2.1(b) gives hanger spacing by pipe diameter (steel pipe except threaded lightwall). In summary:

Pipe diameter	NFPA 13 max.	EN 12845 max.
1" / DN25	3.7 m (12 ft)	4.0 m
1¼" / DN32	3.7 m	4.0 m
1½"–2" / DN40–DN50	4.6 m (15 ft)	4.0 m
2½"–8" / DN65–DN200	4.6 m	4.0 m (6.0 m with the exception)

NFPA is tighter at small diameters (3.7 m) and looser at large ones (4.6 m). EN 12845 gives a single spacing of 4 m and opens an exception for larger pipe. NFPA additionally covers seismic bracing in detail in Chapter 18; on the EN side, A2:2026 leaves this subject to EN 12845-3.

Turkish context

BYKHY Article 96(5) requires sprinkler system design to TS EN 12845, which ties the hanger detail to the standard. Through this link, compliance of the hanger detail with EN 12845 Clause 17.2 and Table 40 can be questioned at permit stage. On the seismic side, Article 96(6) requires, in first- and second-degree seismic zones, four-way bracing of risers, flexible couplings where pipes of 65 mm and larger connect from the floors to the mains, two-way lateral and longitudinal restraint hangers where pipes are fixed to the ceiling, and details at expansion joints that accommodate movement in all three directions. EN 12845 itself does not size these supports; A2:2026 recommends EN 12845-3 for this. Under Article 5(2) the European standard (EN 12845-3) comes first, and internationally recognised standards such as NFPA 13 or FM Global DS 2-8 may be used only for matters it does not cover.

Checklist — before going to site

• Any steel pipe spacing above 4 m? If so, is the exception documented?
• Any copper pipe spacing above 2 m? Is the insulating liner inside the clamp?
• Is there a support within 1 m of every mechanical joint (grooved coupling)?
• Terminal sprinkler to last support: ≤ 0.9 m on DN25, ≤ 1.2 m above?
• Additional support on vertical pipe over 2 m?
• Is any pipe over 50 mm (DN65 and above) hung from corrugated steel sheet or aerated concrete, or any pipe from plasterboard ceiling profiles? It must not be.
• Anchors: steel expansion type, correct M8/M10/M12/M16 size, 30/40/50 mm embedment in concrete?
• Any plastic anchors or nylon ties? There must be none.
• In a seismic zone, is there a sway bracing plan for risers and mains?

Frequently asked questions

What is the maximum hanger spacing on steel pipe?

4 m. Above 50 mm it can be increased by 50 % to 6 m, provided two independent supports are used or a single support carrying 50 % more than the tabulated load.

Why is copper spaced more closely?

Copper's modulus of elasticity is lower than steel's, so it deflects faster. The maximum is 2 m, rising to 3 m above 50 mm with the 50 % exception. An insulating liner is also required inside the clamp to prevent galvanic corrosion.

How far can the last support be from the end sprinkler?

0.9 m on DN25 pipe and 1.2 m above DN25. An upright sprinkler must be at least 0.15 m from the support, otherwise the discharge pattern is disturbed.

Does EN 12845 require seismic bracing?

TS EN 12845+A2:2026 Clause 13.1 recommends applying EN 12845-3 in areas at risk of earthquakes. BYKHY Article 96(6), in addition, requires four-way bracing of risers, flexible couplings where pipes of 65 mm and larger connect to the mains, and two-way lateral and longitudinal restraint hangers in first- and second-degree seismic zones; EN 12845-3 comes first for sizing these supports, with NFPA 13 or FM Global DS 2-8 used for matters it does not cover.

When does a vertical pipe need additional support?

Above 2 m in general, and above 1 m for a drop feeding a single sprinkler. Low-level pipe exposed to mechanical impact is separately supported, though horizontal connections under 0.45 m and vertical drops under 0.6 m are exempt.

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