Koso Hammel vs CCI vs Copes Vulcan 3

[cian85]

Im doing some research on these particular brands regarding their stacked disk laberynth design to control excesive noise and cavitation mainly in power generation applications and oil industry.
It would be quite helpful if you guys could share experiences (good or bad) when working with these brands and if they actually solved any problems you might have had.

Thanks!

 

[valveguru]

Flashing is easy to predict or control. The amount of volumetric expansion on saturted water from 600 psig down to 10 psig is about 250:1. If you have a 25 ft/sec line velocity coming into the valve, the velocity out would be 6000 ft/sec. This of course cannot occur, as downstream velocities would be M = 5, and vena contra velocities would be even higher if 100% of the flash occured at the pressure letdown point. Flashing is not instantaneious. Only partially flashing occurs in the valve and continues to occur throughout the downstream pipe. In some cases downstream pressure backing up into the piping can actually force cavitation at the valve.

There are two ways to handle flashing. One in single stage letdown, where you armour the valve trim and outlet, discharge the flow parallel to the axis of the downstream pipe, provide very robust guiding, and get out of the way. Support the piping well, as the flashing will result in variable two phase flow, and liquid/vapor slugs will momenteum impact into the valve and pipe.

The second method is multistage letdown. For cavitation to occur, vapor bubbles need to form and collapse, and this occurs with velocity accelleration and velocity deaccelleration. Not all trim types have distinct stages with complete velocity recover between stages which is a requiredment for cavitation to occur interstage. Taking multiple stage letdown, armoring the valve trim with hardened stainless, and providing many smaller flow passages can result in lower system vibration and a more uniform flow stream as it discharges out of the valve. Proper material selection of the valve body and downstream pipe is still important.

If you do mount the valve directly to the flash tank nozzle, be sure to calculate jet size and recovery length, as you to not want to tunnel out the flash tank as well.

 

[abscott]

Greetings to all. I have been on assignment for several months.
CCI developed the original "drag" trim and was awarded a patent on the design concept. Twenty plus years ago CCI management wanted to penetrate the asian market place and signed a mutual agreement with KOSO Japan. CCI was granted the rights to sell the KOSO valve line in North America and KOSO Japan was granted the rights to design, manufacture and sell the CCI "drag" trim for the asian Market. CCI transferred the "drag" trim technology and manufacturing processes to KOSO Japan.
CCI never succeeded selling the KOSO line but KOSO has a 20 year history of selling severe service valves with "drag" trim in the asian market. In 2002 the agreement ended and after a 5 year non-compete period (2007) Koso Japan transferred the CCI drag technology to KOSO America, Hammel Dahl.
Bottom line - Hammel Dahl "Stacked-Disc" trim is the CCI drag trim with improvements.
Hope this helps,
abscott

 

[UHoustonMSME]

I was in Japan some years ago and heard story that the Koso implementation of DRAG was a disaster, with parts not fitting together, and these Koso designs being cut out. I also never heard of any Hammel Dahl "stacked disc" valves in America. Does anybody else know anything about this?

 

[valveguru]

Koso Japan was a licensed manufacture of CCI Drag trim. They were given drawings and produced hardware from 1" through 8" 600# valves. These valves were designed for intermediate service, not for severe service. This licensing agreement was terminated a number of years ago, and the technology given to KOSO was 20 to 30 year old technology, not involving high pressure or high temperature service valves.

Hammel Dahl has produced catalogs of multi-turn technology, advertising its KOSO technology. The current web site for Hammel Dahl has very little on service service applications, most of which is "coming soon". I keep hearing on how others have "improved" on the original CCI design, but the CCI design has not been stagnant and has a number of innovations over the years.

The key to success in severe service applicatons is operational experience with installed base. Anyone can generate pretty catalogs and CAD pictures. I saw one catalog from a vendor who claimed to build multiturn 1" -36" size valves, 150# to 2500# ANSI. Their company consists of 5 people, 1 engineer, a total company sales volume of $5 million (mostly conventional valves). But they do advertise multi-turn trim, and they will probably give you a cheap price on your severe service valve.