Dual mechanical seals
Dual mechanical seals
(OP)
Dear Sir/Madam,
Would you please explain when dual mechanical seals are used? I konw fr the hazardous services (toid,...)dual mechanical seal are used.
We have some centrifugal API 610 pumps with hydrocarbon fluid (Aromatic Feed, Naphtha,...) with discharge pressure 13 barg. Some famous manufacturer like Sulzer, KSB... presented dual mechanical seal with plan 52 and 53B. There is not any available utility in our site for their consumption.
Some other manufacturers presented single mechanical seal! I don know whay dual mechanical seals are needed?
Thanks
Would you please explain when dual mechanical seals are used? I konw fr the hazardous services (toid,...)dual mechanical seal are used.
We have some centrifugal API 610 pumps with hydrocarbon fluid (Aromatic Feed, Naphtha,...) with discharge pressure 13 barg. Some famous manufacturer like Sulzer, KSB... presented dual mechanical seal with plan 52 and 53B. There is not any available utility in our site for their consumption.
Some other manufacturers presented single mechanical seal! I don know whay dual mechanical seals are needed?
Thanks





RE: Dual mechanical seals
Find the rest here, http://www.mcnallyinstitute.com/08-html/8-8.html
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"Pumping accounts for 20% of the world's energy used by electric motors and 25% to 50% of the total electrical energy usage in certain industrial facilities." - DOE statistic (Note: Make that 99.99% for pipeline companies) http://virtualpipeline.spaces.live.com/
RE: Dual mechanical seals
The problem is that there arent any avilable utility at our site. The site will be new Tank farm and there are much process pumps to pumpig the hydrocarbin into the ships. As I mentoned there are not any source of air, cooling water,...for this meen and also manufacturers recommended dual mechanical seals for some pumps! Medium fluid of all pumps will be hydrocarbon and some pumps submitted with dual mechanical seals! Others are single!
Whay we should do for this?
Thanks agin,
RE: Dual mechanical seals
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"Pumping accounts for 20% of the world's energy used by electric motors and 25% to 50% of the total electrical energy usage in certain industrial facilities." - DOE statistic (Note: Make that 99.99% for pipeline companies) http://virtualpipeline.spaces.live.com/
RE: Dual mechanical seals
RE: Dual mechanical seals
API Plan 53 refers to the support systems for dual seals.
53A is the most common installation- a Nitrogen header used to pressurize a seal reservoir.
53B is less common and utilizes an accumulator to provide pressure for the barrier fluid between the seals. This could be an option for a tank farm provided that the end user has adequate instrumentation to notify operations or maintenance that the barrier fluid needs to be topped off, or that the accumulator bladder needs to be refreshed.
53C is even less common and uses a piston pot tied into the discharge or seal chamber of the pump to provide a reference pressure for the pot. Again, instrumentation would be required.
Cooling for these plans may also be an important consideration. If cooling water or other fluid is unavailable (as mentioned above) an air cooled heat exchanger may also be used to cool the barrier fluid. When specifying an air cooled exchanger your local environment is an important factor. Salty air or high humidity for example may need to be dealt with.
Your best off discussing each application with your preferred mechanical seal vendor. They may have other options or can further discuss the reasons for the multiple seals in your services.
RE: Dual mechanical seals
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"Pumping accounts for 20% of the world's energy used by electric motors and 25% to 50% of the total electrical energy usage in certain industrial facilities." - DOE statistic (Note: Make that 99.99% for pipeline companies) http://virtualpipeline.spaces.live.com/
RE: Dual mechanical seals
Hydrocarbons in a tank farm?
Use a single seal and vent the vaporised leakage off to the top (vapour section) of the tanks.
To reduce the leakage a tandem seal could be used. Just connect the cavity between the first and the second seal to the suction side via an orrifice plate. That way you will be sealing on suction pressure and not seal cavity pressure. That will reduce the leakage.
Traditional hydrocarbons should vaporise off over the seal face so hooking up to the vapor side of the tanks should not be an issue.
By the way a double seal does not provide a backup seal as only one seal is ever sealing to the outside. Tandem seals do provide a backup seal
A double seal is used for one reason. To make sure that absolutely no pumped product leaks to the outside.
Regards
Scalleke
RE: Dual mechanical seals
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"Pumping accounts for 20% of the world's energy used by electric motors and 25% to 50% of the total electrical energy usage in certain industrial facilities." - DOE statistic (Note: Make that 99.99% for pipeline companies) http://virtualpipeline.spaces.live.com/
RE: Dual mechanical seals
Sometimes this can make applications more difficult- like crude oil. This is an easy application for a single seal. In my experience dual unpressurized seals have a more difficult time with this fluid due to heat generation and high viscosity. Crude oil in the buffer fluid does no favors. Again, your prefered vendor's experience and knowledge of their product line is invaluable.
RE: Dual mechanical seals
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"Pumping accounts for 20% of the world's energy used by electric motors and 25% to 50% of the total electrical energy usage in certain industrial facilities." - DOE statistic (Note: Make that 99.99% for pipeline companies) http://virtualpipeline.spaces.live.com/
RE: Dual mechanical seals
For satisfactory performance, the liquid in the seal area should remain in liquid state all the time. To ensure this whatever minimum utilities are required, please use the same. Do not go for unnecessary factor of safety.