Keystone International, headquartered in Houston, Texas, was a major manufacturer of butterfly valves, ball valves, and related pipeline equipment for industrial and naval applications. Keystone supplied the US Navy with large-bore butterfly valves for use in seawater systems, fire main systems, and large-diameter auxiliary piping applications aboard surface ships and at shore facilities. Keystone butterfly valves incorporated asbestos-containing seat liner materials in the valve seat construction and asbestos-containing packing materials in the stem seal of these large-diameter valves. Navy Machinist’s Mates and engineering ratings performing butterfly valve maintenance — including seat replacement, stem repacking, and valve overhaul — worked with asbestos-containing valve component materials during valve maintenance operations.

Asbestos in Keystone Butterfly Valve Products

Keystone butterfly valve products incorporated asbestos in valve construction:

  • Butterfly valve seat materials — Keystone butterfly valves used asbestos-containing resilient seat liner materials for valve seat construction in higher-temperature steam and hot water applications. These asbestos-containing seat materials provided the resilient sealing surface for the butterfly disk closure and incorporated asbestos fiber for thermal resistance in the seat construction. Machinist’s Mates removing and replacing Keystone butterfly valve seats during overhaul encountered asbestos-containing seat materials during the seat removal and replacement procedure
  • Valve stem packing — Keystone butterfly valve stem seals used asbestos packing materials in the stem seal gland to prevent leakage around the valve shaft. Engineering ratings performing valve stem repacking operations on Keystone butterfly valves encountered asbestos-containing stem packing materials during gland nut removal and packing replacement
  • Valve body thermal insulation — large-bore Keystone butterfly valves installed on high-temperature service piping were insulated with asbestos-containing pipe covering and asbestos block insulation applied to the valve body and adjacent piping, with engineering ratings working in proximity to this asbestos insulation on insulated Keystone valve installations

Keystone butterfly valves appeared in Navy large-bore piping systems:

  • Seawater service and cooling systems — large-bore butterfly valves controlled seawater flow in engineering space cooling systems and seawater service systems, with Keystone and competitor manufacturer butterfly valves providing isolation and throttling control in these large-diameter seawater piping applications

VA Claims for Veterans Exposed to Keystone Products

VA presumptive service connection under 38 CFR § 3.309(d) covers asbestos exposure from valve maintenance in Navy engineering spaces. Machinist’s Mates and engineering ratings who performed butterfly valve maintenance on Keystone and other manufacturer valves with asbestos seat and packing materials and have since been diagnosed with mesothelioma, asbestosis, or asbestos-related lung cancer may qualify for VA disability benefits.