Boiler tip of the month – Challenges in pipe routing of steam pipes II
Installation and assembly errors occur now and again because in larger projects, several companies are often working together for the first time. Many interfaces and many installation instructions of specific manufacturers must be observed. Time pressure which is often an aspect of such projects can also have a decisive effect. The various trades install their pipework without coordinating with one another and whoever arrives on-site first installs first without taking the following installations into account.
In these situations problematic faults occur, e.g. a volumeter installed in the incorrect flow direction or incorrect connections at a heat exchanger or at safety valves which come to attention during commissioning and must then be rectified. Unfortunately, often systems and pipework are either poorly or not perfectly installed. The following problems are either not or only partially identified during commissioning and acceptance of the system, which then leads to a permanent deterioration in operating conditions.
Merging of pipework
Merging of pipework with the same function is a standard procedure in plant engineering. It goes without saying that steam pipes from several boiler systems are combined into one supply pipe with suitable nominal diameter, for example. However, this is only possible if the function is not impaired. This can lead to severe problems, particularly in the case of safety valve blow-off pipes.
Safety valve blow-off pipes must always be routed separately to the open air and, whenever possible, via the most direct route. When pipework is merged, this affects the function of the safety valve and the necessary blow-off quantities are undercut. As the reaction forces that occur when the valve responds are high, the pipe could even break off.
Problems:
- Impermissible increase in pressure in the boiler possible
- Safety function no longer exists
- Infringement of the regulations
- Possible break in pipework
Cause:
- Excessively high flow resistance in the pipework
- Retroactive effect on the safety valve (flutter)
Remedy:
- Always route the blow-off pipes of the various safety valves separately