Specifying right valve, materials key to proper fluid control

Oct. 1, 2001
Fluid control systems rely on valves to control the flow of fluids in all industrial processes, mobile transports, and fixed or floating offshore production systems.

Fluid control systems rely on valves to control the flow of fluids in all industrial processes, mobile transports, and fixed or floating offshore production systems. Depending on the fluids brass, bronze, steel, or titanium valves may be required. Laholm Industrier offers a complete spectrum of valves in a wide variety of DN standards.

Laholm is a DIN specialist and produces globe valves in sizes ranging from DN8 to DN450, gate valves from DN10 to DN800, mud boxes and strainers up to DN 500, and butterfly valves up to DN600. Check valves are available in an assortment of shapes and dimensions from DN10 up to DN 600.

Gate valves come in many sizes and styles to fit industrial and marine applications.
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Gate valves come in two major styles: rising and non-rising stems. In the rising stem style the stem (a threaded shaft) is attached to the closing wedge. The stem rises through the threaded handle which protects the stem threads from corrosive media. This is important when aggressive fluids are being transported and where valve integrity is key. The fully opened valve provides unrestricted movement of the fluid. Rising stem gate valves are best for high pressure applications.

Often metal seats have problems with leakage. Laholm produces valves with Teflon seats to assure full closure. If the fluid is carrying small particles, the Teflon seats will flex slightly to accommodate the particles trapped by the closure of the valve.

Non-rising stem gate valves are for less rigorous environments. The shaft is fixed within the base of the valve and is attached to the handle. As the handle is turned the closing wedge moves on the stem. Since the stem is always within the flowing fluid, the stem does create some turbulence in the flow and can be affected by the fluids.

These valves are best for lower pressure applications and the choice of valve material can be important depending on the fluid being moved. To this end, the company offers valves in many different metals including Rg 5, Rg 10, Alu-bronze, GG-25, GGG-40.3, AISI 316 and GS-C25.

Snorre's titanium valves

Other materials can be ordered by special request. One example of this capability is the high specification titanium valves built for the Snorre platform. Because of the fail-safe nature of the platform's major control valves at the seabed, 10 titanium valves were built to control the flow of raw crude oil and natural gas into the platform from the wells. The valves continue to operate as expected with no performance problems.

Laholm Steel produces centrifugal cast steel tubes in stainless steel, acid proof, and heat resistant grades. These are machined into rings, sleeves, bushings, and other devices. By using a centrifugal casting process (rotating the steel mold while pouring), the metal solidifies into a dense, sound casting. Diameters from 70 mm to 750 mm can be made with wall thickness of 8-80 mm.

Laholm uses MPS computer controlled lathes to get the highest quality and consistent production of valves. This August, a new heat treating oven for stainless steel was installed to provide semi-finished products for other manufacturers.

For more information, contact Claes Alfort, Laholm Industrier AB: Tel: +46 430 736 11, Fax: +46 430 131 87, e-mail: [email protected] .