5. Steam Piping. Flashcards
- List 4 factors to be considered to ensure trouble free operation of a steam steam piping system?
- Air elimination.
- Draining of fluids.
- Pressure differential.
- Expansion.
- Why is pipe size an important factor in the distribution of steam in a steam heating system?
Different volumes of steam can be delivered through different size pipe at a specific pressure. In order to insure the proper amount of steam is delivered to each heat unit, the correct size pipe must be installed in each part of the system.
- How should steam mains be pitched down?
Run in direction of flow not less then 1” per 20’ of run.
- How should return mains be pitched?
Not less than 1/2” per 20’ of run.
- What takes place when horizontal steam piping is installed without uniform pitch?
Improper or insufficient support can cause a water pocket to form due to a sag in the piping. It can cause water hammer when steam reaches the water pocket especially on cold start up, or the free flow of steam air and condensate is impossible.
- What are some causes of water hammer in steam piping?
The steam flowing over the condensate, creating slugs of water. This slugs of water will not only create noise, but can also destroy valves, steam traps vents.
- How may steam mains be supported?
- From the ceiling by hangers.
- On the wall by brackets.
- From the floor by stands.
- The allowances must be made for the pipe insulation.
- The piping should never be attached to a support in such a way that it can not move.
- What for are a pipe saddle?
They are tack welded to the pipe used on steam and high temperature water system and protect pipe insulation against damage caused by pipe movement.
- Why is removal of condensate an important consideration on long runs of horizontal piping?
In order to keep steam as dry as possible, steam traps should be installed on long horizontal runs of piping at intervals of 150’ to 300’.
- How are drip connections installed in steam heating system?
- For vapor system the end of steam mains may be dripped directly into the wet returns and the air vented through a thermostatic trap. A steam trap is not required.
- Steam mains that are tied into a dry return must utilize a steam trap.
- Size of the steam main dirt pocket?
It should be at least 10” long and at least 2” in diameter.
- What is dirt pocket for in the steam main?
It collect any heavy foreign materials such as scale or pipe cuttings that might other wise enter the steam trap and interfere with satisfactory trap operation. This foreign material settles in the bottom of the dirt pocket when the system is first put in operation. The cap on the bottom of the dirt pocket should be removed and dirt pocket cleaned several times during the first heating season. Such attention is usually not required.
- How is expansion that takes place in the piping used in steam mains and risers controlled?
A common way of dealing with this problem is to install an expansion joint.
- Give a brief description of the operation and installation requirements for a single joint slip type sleeve expansion joint?
As the pipe lengthens the sleeve is forced back into the casing. The is kept tight by means of a packing material. The type of packing material determines the joints temperature limit. The packing material is usually a compound of teflon, graphite or other suitable material. The casing side of the joint must be firmly anchored. On the sleeve side of the joint, guides must be installed.
- What is the reason for pipe tapping on the bottom of the casing of single-slip type sleeve expansion joint?
A steam trap must be installed here so there is no chance of water collecting in the expansion joint.
