It is common practice for large, natural gas-fueled, stationary generator engines to utilize cobalt-base common trade materials for valve and insert components. These generators are used for routine power generation in oil field and oil rig installations and for backup power at hospitals and other facilities using smaller power generation engines. The cobalt-base components typically found in these engines are expensive and contain 50 percent cobalt that historically has cost as much as $35 per pound. In today’s global marketplace, driven by fierce international competition, engine manufacturers are looking for ways to cut costs. Increasingly, these reductions are aided by the substitution of iron-base materials to replace cobalt-base common trade materials in valve seat insert components.

W77T6-P®, which was specifically designed to replace a cobalt-base common trade material, has been successfully used in a variety of natural gas engine applications. One smaller generator application used to provide power to hospitals, nursing homes, and small hotels has a total displacement of about 11L with an engine speed of approximately 1800 rpm. In this application, the cobalt-base common trade materials used for the intake insert and valve had total recession wear of 0.01 mm and the exhaust was 0.10 mm after about 3500 hours of testing. The substitution of W77T6-P® yields intake and exhaust recession values of 0.02 mm and 0.05 mm, respectively. In this case, the W77T6-P® intake results in more wear, but is well within the objective and the exhaust combination has half as much wear as the expensive cobalt-base common trade material. The change was made more than five years ago and has generated significant savings for the OEM customer. For both material combinations, the contact surfaces showed a similar pattern of mild adhesive wear.