Radiator nipple: functions, replacement, sealing

What functions does the nipple for heating radiators? How does it work? How to replace a broken nipple and how to ensure the tightness of the connection after its replacement? In this article we will try to answer the listed questions.

What it is

Sectional radiators are the most common, among other things, due to the possibility of flexible adjustment of the heat transfer device. If its efficiency is insufficient, you can always add a few more sections, increasing the heat output. It is clear that their price is incomparable with the cost of a new convector or a large radiator panel.

The nipple for the radiator, in fact, provides their connection to each other. It is a short tube with opposing threads, which are simultaneously screwed into two adjacent sections, attracting them to each other. Inside it is equipped with a pair of protrusions for the radiator key.

The thread diameter of the nipple and, accordingly, of the section collectors is:

As materials in the production of nipples are used:

• Ductile iron;
• Steel.

Useful: steel products are much stronger at the gap, but they have less corrosion resistance. If the heating system is discharged for the summer, then a radiator cast iron nipple is preferable: it will make it possible to do much less effort when disassembling the heater.

Problems

What problems of sectional heating devices somehow related to the nipples?

Intersectional leaks

The reason for their appearance is that the gaskets between the sections tightened by the nipple gradually lose their elasticity due to prolonged heating and liming. With each heating and cooling the linear dimensions of the sections change slightly; while the strip is deformed over and over again.

Finally, during the next cooling of the battery, it ceases to completely block the gap between the collectors of the sections, and moisture appears at the junction.

Nipple break

Much more unpleasant with its consequences is the nipple break. If in the first case the worst that you face is a small puddle under the battery, then disconnecting one of the collectors is fraught with flooding your and neighboring apartments with hot water with plenty of silt and sand.

What could be the reason for breaking a sufficiently durable nipple?

• Overloaded during assembly. As already mentioned, the sections expand somewhat when heated; if the temperature of the coolant increases, a barely visible crack will expand and become a source of serious problems.
• Water hammer. This is the name of a wave propagating in a practically incompressible medium, created by abruptly stopping the flow when the valve of the screw valve is pulled off, the gate valve drops or just shut off valves. The pressure at the flow front at the water hammer can reach 20-25 atmospheres.

Reference: cast iron radiators are designed for a working pressure of 9-12 atmospheres, aluminum - 6 - 16.

Sealing

What ensures the tightness of intersectional joints?

• Up to the middle of the 20th century, sanitary flax with lead red lead was used for this purpose. The paint prevented natural fiber from burning out at high temperatures and damping when wetted. The winding was placed around the nipple in a tight bundle and reliably tightened when joining the sections.
• The next few decades in the factory assembly of cast iron heating devices used paronite gaskets (hard heat-resistant rubber). The solid resource of this material is combined with low elasticity, requiring a great effort of tightening.

• Now for sectional aluminum, cast iron, steel and bimetallic batteries, along with paronite, silicone gaskets are used. They are distinguished by a toroidal section (in other words, they look like a thin bagel). Silicone retains its elasticity for a long time and does not require a great effort of tightening.

However: when assembling an intersectional joint, it is rather difficult to center the gasket so that it does not squeeze out of the sections. Silicone rings more convenient to use with sections that have annular grooves on the planes of the collectors.

Replacement

How to replace the gasket between the sections or intersection nipple?

Here is the replacement instruction for when the problem connection is close to the end of the radiator:

1. After discharge of the coolant, blind plugs are turned off.
2. On the radiator key, the marker indicates the distance to the problematic connection.
3. The key is inserted into the radiator and turns to engage the nipple ribs.
4. The nipple turns clockwise (from the side of the blind plug the thread is always left) one turn.
5. The operation is repeated with the second nipple. Then they turn away alternately: a misalignment can jam the connection or simply break the nipple.

After replacing the defective part, the assembly is carried out in the reverse order. If the problematic connection is close to the liner, the radiator is dismantled and disassembled on the floor.

When repairing sectional radiators it is useful to know a couple of subtleties.

• If the connection does not give in to the key, warm the section collector with a blowtorch or a building hairdryer. Due to the temperature expansion, the force required for disassembly will become quite feasible.
• If you do not have ready-made radiator pads on hand, you can make them yourself. Cut the unwanted car camera, circle on it the contour of the old gasket with a ballpoint pen and cut out the new gasket with ordinary scissors.

Conclusion

As you can see, the repair of sectional heating devices does not require high qualifications or any special skills. The video in this article will help the reader to learn more about it. Successes!