Resisting Corrosion

Harsh environments call for corrosion-resistant materials. Some environments, for example in marine or underwater applications, require machines and components with an exceptionally high resistance to corrosive elements.

One example is the actuator connection shafts for an undersea oil valve actuator. The installation is located on the ocean floor, some 100 metres (330 ft) below sea level.

Some of the valves are opened and closed by small submarines. To allow the submarines to operate the valves from a safe distance, the valves are fitted with articulated shafts. Articulated shafts also transfer the actuation movement and force to other parts of the system.

The shafts are constructed like telescopes to allow changes in length to adapt to small movements and to the relocation of the equipment’s position. The complete shaft assemblies are easy to disassemble for transportation and reassemble for refitting.

Due to the extremely harsh underwater environment, all components must have an exceptional resistance to corrosion. In this case, the supplier of the actuator connection shafts, Belden Inc., used a higher-grade stainless steel for the universal joints. The yokes of the universal joints are made of extremely corrosion-resistant 316L stainless steel. In addition, to prevent galling and to improve the joints’ friction properties, the yokes’ contact surfaces are PTFE-coated. The pins and blocks are also manufactured from 316L stainless steel and are protected with grease-packed boots.

To provide higher strength and improved wear resistance, Belden’s standard stainless steel joints have AISI 303 stainless steel yokes and AISI 416 steel pins and blocks. Standard single joints can be modified with a variety of stainless steel grades, including 304, 316, 17-4 and 15-5, to meet specific application requirements. Diameters range from 13 mm (1/2 in.) to 153 mm (6 in.) with a standard operating angle of 35 degrees.

From underwater oil field equipment to drinking water conveying systems and food processing applications, Belden’s universal joints and complete shaft assemblies are available in a variety of stainless steel grades and with various hub configurations, lubricants and additional protective measures such as boots, for use in a wide range of applications in even the most corrosive environments.

The specialty of Broadview, Ill., based Belden lies in custom assemblies and unique manufacturing processes to produce small batches as cost-effectively as high-volume standard universal joints.