CLAMSHELL BELLOWS Clamshell bellows is the optimum solution when a quick and unexpected replacement of the bellow is necessary. This is done with a minimal down time and result enormous cost-savings. Clamshells are used in all kinds of pipelines for example on steel plants.
What is clamshell belllows? Clamshell bellows is two-piece bellows which is welded around the current bellow. It is assembled and welded on-site. Clamshells can be designed as a non-permanent or as a permanent solution. It is important that the clamshell bellows is installed as soon as possible after the failure, eventually a leakage, is discovered. As an eventual crack in the bellow quickly increases. There are two kinds of clamshell bellows: Over-size-clamshells and same-size-clamshells.
Over-size-clamshell bellows This kind of clamshell bellows is installed on top of the current bellow while the system operates for which reason down time is not necessary. It is unnecessary to open the pipeline as the current compensator is not removed. Likewise entrance to the inside of the pipeline is not necessary. If down time, at the given time, is not possible a non-permanent solution like over-size-clamshells is chosen.
Same-size-clamshell bellows This kind of clamshell bellows has the same size as the current bellow in the pipeline. The current bellow is removed before installation of the clamshells. This means a short down time. Same-size-clamshells is primarily chosen if a permanent solution is required.
Belman's installation team helps At installation experience with installation of this kind of compensator is an advantage. The customer often finds it safer if Belman carries out the installation of their clamshell. The company has a team of experienced welders that do installation jobs.
A job completed by the installation team Lately the installation team has installed two clamshells at the blast furnace on a steel plant in Great Britain. The problem was that coke gas leaked from a leakage in the current bellow. As for safety this carbon monoxide gas (CO) constitute a major problem. Down time was not an option and therefore an alternative solution was needed.
The solution was two over-size-clamshells which were installed on top of the current bellows. These clamshells are designed according to the current bellows and the operating data of the plant. These clamshells can now operate until the next shut down and at that time these are replaced with a permanent solution. Steel plants often chose clamshells as it is very expensive for them to shut down the plant.
Belman’s installation team installed these two over-size-clamshells without opening the pipeline. They are installed in the pipeline that leads coke gas from the blast furnace to incineration in the gas turbine, for generating electricity. More precisely the clamshells are placed between the cyclone and the gas turbine. The installed clamshells are NB 4000 mm, and 500 mm long. The design temperature is 350ºC and the design pressure is 2,8 bar. They absorb 0,98º angular movement. The bellows are made from Incoloy 825 and the welding ends from P265GH.
Belman has great experience in design, manufacture and installation of clamshell bellows, which are designed and manufactured as both round and rectangular and from NB 400 to more than NB 6000 and in many different materials.
