ASTM A860 WPHY65 Large-Diameter Pipe Cap Specifications at a Glance: 88 IN O.D. · 23.83 MM THK · H = 457 MM · ASTM A860 Grade WPHY65 A Fitting Built at the Limits of Large-Bore Fabrication Not every pipeline project fits neatly into a catalog. When a project calls for an 88-inch pipe cap with close to an inch of wall steel, standard production logic no longer applies — you’re in the territory of purpose-built forming, careful heat treatment management, and dimensional checks that leave no margin for rework in the field.