Pipe penetration seals - insulation, hanging, pipe wall thickness and pipe end configuration

Our sealing solutions are classified according to European Standards, and all our products come with a European Technical Approval (ETA). This means there are no restrictions for their application within EU countries.

Penetration seals

Modern architectural passive fire protection is based on the principle of sub-dividing the building into fire compartments. In other words, the building must be segmented vertically and horizontally into fire compartments of various dimensions. Surfaces bordering fire compartments must prevent the penetration of fire and smoke, which can only be achieved by the installation of fire stopping systemss. Today's  buildings include a wide range of electric and mechanical pipe systems for crictical services. Some compare these services to the vascular system in our body.

The holes adn gaps created by services  (penetrations) need to be closed (sealed) by fire stopping solutions that have been fully tested according to the European Test Standard (EN 1366-3) and classified according to the EN 13501-2 Standard. Mo other type of classification can be applied. This article aims to stress the importance of these legal requirements and to describe the certified Promat solutions. If you want to comply with the classification standard it is important to choose and install the correct penetration seals.

Local legislation dealing with fire spread protection offers numerous solutions for firestopping pipe penetrations. It goes without saying that the penetration of a combustible pipe or that of a metal pipe have to be sealed differently. Moreover, it is important to know whether the penetrating pipe is insulated or not, and the system to be applied depends on the material quality of the insulation. The EN 1366-3 Test Standard covers a lot of these criteria. The table below contains a simple list of test arrangements depending on each pipe type:

Due to the limitations of the scope of this article, we will cover only materials and diameters of pipes, wall thicknesses, insulation and pipe end configurations. 

You will be confronted with four possible cases, depending on the arrangement of pipe insulation in the penetration:

1. CS (Continued Sustained): the entire length of the pipe is insulated and the insulation passes through the penetration’s cross section;
2. CI (Continued Interrupted): the entire length of the pipe is insulated but the insulation is interrupted in the penetration;
3. LS (Local Sustained): the pipe is insulated only in the vicinity of the penetration and the insulation passes through the penetration’s cross section;
4. LI (Local Interrupted): the pipe is insulated only in the vicinity of the penetration and the insulation is interrupted in the penetration.

The insulation – depending on its relevance to fire classification – might be used in the penetration (as part of the system) or it might form the penetration by itself, although additional insulation might be required, and this is not shown in the drawing. The technical manuals include the above-stated details. With the help of mineral wool, metal pipes can pass through soft penetrations by using PROMASTOP®-CC coating with non-combustible insulation in LS or CS configurations (i.e., sustained insulation locally or over the entire length of the pipe).

Pipe wall thickness and insulation

Generally speaking, shorter compartment insulation is suitable for metal pipes with a smaller diameter, smaller wall thickness and lower thermal conductivity: with PROMASTOP®-CC soft penetrations of metal pipes with low thermal conductivity (λ ≤ 58 W/mK), pipe wall thickness 2,0 mm – 14,0 mm and pipe outer pipe diameter up to 42,0 mm require a non-combustible local insulation total centered penetration length of 500 mm; steel pipes with larger pipe wall thickness or outer pipe diameter need a minimum of 1000 mm long local insulation.

 According to the EN 13501-1 Standard, the reaction to fire classification of the local insulation in PROMASTOP®-CC soft penetration is a minimum of A2-s1, d0 or A2L-s1, d0; its melting-point is a minimum of 1000°C, bulk density is between 40 and 150 kg/m³, and thickness is between 30 and 100 mm. (Warning: this data is not the material characteristics of the mineral wool boards forming the soft penetration itself, as these are covered by a special provision; the thickness in the referred penetration is 1 x 50 mm, 1 x 80 mm or 2 x 50 mm, and the bulk density is minimum 140 kg/m³). The minimum required local insulation length for copper pipes with larger thermal conductivity (λ ≤ 380 W/mK), pipe wall thickness up to 14,2 mm and pipe outer diameter up to 42 mm, is 1000 mm; copper pipes with a larger outer pipe diameter (up to 88 mm) need a minimum of 2000 mm long local insulation.

Not only Promat solutions require this complicated system, but all producers are expected to present the required insulation length in this way, according to the Test and Classification Standard.

Pipe end configuration

According to the EN 1366-3 Test Standard, four possibilities are determined based on the design of the metal or plastic pipe ends passing through the tested penetration, depending on whether the end of the tested pipe was closed inside and outside of the furnace (Capped, marked C) or was open (Uncapped, marked U).

The behavior of the specimen during the test is fundamentally determined by the design of the pipe end: the pressure and flow of hot gases are different in (an open) pipe that is in contact with the atmosphere than in a capped pipe, so when choosing the suitable fire protection solution the proper pipe end configuration must be taken into account as well, and not just the usual EI XX fire classification. Certainly all readers have already seen the U/U or U/C mark in the fire classification of a modern fire collar, which was explained above (i.e. a pipe open on both ends has a U/U configuration, which is the worst-case scenario from a fire protection point of view, so all solutions with this classification are suitable for any pipe ends).

Let’s take a look at these marks referring to the given installation positions and structural establishments in the classification of fire-stopping collars PROMASTOP®-FC (powder-coated stainless-steel body with intumescent inlay) and PROMASTOP®-FC MD (cut-to-length collar) and PROMASTOP®-W fire-stopping wrap. The pipe end classification may differ in light or solid wall, in a soft penetration or core drilled hole, in wall or floor penetration.

Service support construction

All penetration seals are capable of performing their function as long as they are unharmed, which requires suitable, stable hanging or support. During the test the manufacturer determines the distance of the first service support construction from the surface of the penetration, and this distance must not be increased by applying the penetrations in practice. Pipes must be supported at a ≤ 250 mm distance in a PROMASTOP®-CC soft penetration on both sides of the wall or from the top of the floor to avoid excessive load of the mineral wool boards in the soft penetration. The supporting distance must be checked for each product in the related manual.

What should you take into consideration?

These are the most important elements you should pay attention to when designing or planning a penetration seal:

• thickness, bulk density, reaction to fire classification and melting point of the mineral wool boards in soft penetrations;
• required thickness of the applied coating;
• length, thickness, bulk density, reaction to fire classification and melting point of the local insulation;
• whether the classified pipe end configuration is suitable for the building position;
• distance of the first suspension/support from the soft penetration.

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