1.1 ,This specification covers electric-fusion (arc)-welded straight seam or spiral seam steel casing pipe 10 in. (254 mm) and larger in diameter (outside diameter as specified by purchaser) with wall thickness 0.200 in. (5.1 mm) or greater. It shall be permissible to specify and furnish pipe having other dimensions provided such pipe complies with all other requirements of this specification. The pipe is intended for use as casing or encasement in horizontal underground boring, tunneling, or open trench applications.