Fire-resistant fastening: pipes and support structures that stay up in a fire
6 min read
When a pipe passes through a fire separation, that separation must afterwards be just as fire-resistant as before. The fixing is part of that too. If anchors, channels or clamps fail in a fire, the pipe falls down and the seal of the penetration can tear open. This article is about that part of the work: fixings that keep their load capacity in a fire.
WBDBO in brief
WBDBO stands for weerstand tegen branddoorslag en brandoverslag (the Dutch term for resistance to fire penetration and fire spread). It is the time in minutes that a separation holds back a fire. The Besluit bouwwerken leefomgeving (Bbl, the Dutch building regulations) sets requirements per situation, usually 30, 60, 90 or 120 minutes.
A separation is only as strong as its weakest point. A badly sealed penetration in a wall rated at 60 minutes no longer reaches 60 minutes at that spot.
Two parts that must work together
- The seal of the penetration. You make it with a firestop system that is tested for the combination of wall and pipe. Follow the instructions of the manufacturer of that system.
- The fixing of the pipe and the support structure. It must keep carrying load for long enough. Otherwise a falling pipe pulls the seal apart.
What does a fire class say?
For fixings, a class such as R30, R60, R90 or R120 shows for how many minutes the component keeps its load capacity under the test conditions. Which class you need follows from the fire resistance requirement of the building element.
Many fire tests of installation fixings were done according to the MLAR, the German guideline for pipe systems, or according to European test standards such as EN 1363 and EN 1366. The test report states the size, the load and the installation method for which the class applies.
Fixings with fire data in our range
The data below comes from the product information in our webshop.
| Product | Function | Fire data |
|---|---|---|
| FZEA II hammerset anchor | Anchor in cracked and non-cracked concrete | R120 |
| EA II hammerset anchor | Anchor in non-cracked concrete | R120 |
| FAZ II Plus bolt anchor | Anchor in cracked and non-cracked concrete | Design values for load in a fire in the ETA |
| FRS-L Universal pipe clamp | Pipe clamp | R120 (MLAR) |
| FASM and FASH sliders | Sliding point for expansion | Fire test report R30 to R120 (MLAR) |
| FHS Clix T-head bolt | Clamp on channel | R120 |
| PSF saddle flange | Channel to the base material | R120 |
| PDH pendulum hanger (M10 and M12) | Swivelling suspension | F120 fire test, F30 according to MLAR |
| FLS 37 channel and ALK 37 cantilever arm | Support structure along wall and ceiling | Fire inspection report (MLAR, EN 1363-1) |
| FCA cantilever arm | Support arm for pipes, ducts and cable trays | Fire inspection report (MLAR, EN 13501) |
| PUWF angle bracket | Support structure with FUS channels | Fire test report (MLAR, EN 1366) |
In the webshop, these products show the value "Fire classification" under Certification. Always check in the test report for which size, load and installation method the class applies.
What to look for during installation
- The whole assembly counts. A fire class says something about an assembly of anchor, threaded rod, channel and clamp. One component without fire data makes the whole suspension weaker.
- In a fire, it may carry less. The permitted load in a fire is lower than at normal temperature. Calculate with the values from the test report.
- Anchor and base material belong together. An anchor with R120 in concrete says nothing about the same anchor in another base material. Check in the ETA for which base material the fire class applies.
Documentation at handover
For fire-resistant penetrations, an inspector asks for proof. Make sure you have this ready for each project:
- For each penetration: type of firestop system, manufacturer and test or ETA number.
- For each fixing point: type of anchor and clamp, ETA or test report number and fire class.
- Photos of every penetration and every fixing point before they are covered up, with date and location.
- A statement that the penetrations were installed according to the instructions of the manufacturer.
This article is general information, not design advice. The text was checked on 21 October 2026 against the sources below. The design of your installation and the certifying body decide what applies in your project.
Sources
- ETA-19/0520 for the FAZ II Plus (DIBt)
- fischer product page bolt anchor FAZ II Plus (in German)
- fischer product page hammerset anchor FZEA II (in German)
- fischer product page hammerset anchor EA II (in German)
- fischer product page pendulum hanger PDH (in German)
- Product data and approvals per product: the Certification property in our webshop
Order fire-tested fixings
For the products in the webshop, you see under Certification whether there is a fire classification.
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