5.9　Caps

5.9.1　Caps should be ellipsoidal or spherical type.Butt welding flat caps may also be used instead.

5.9.2　The piping with PN≤25 may adopt flat welded caps，welded caps with reinforcement or conical caps.

5.9.3　Caps strength calculation shall comply with the provisions in 6.7 of this code.