ASME Three-Piece Titanium Ball Valve Gr1 Gr2

ASME Three-Piece Titanium Ball Valve Gr1 Gr2

A three-piece ball valve is chosen for one reason: the centre section can be unbolted and swung out of the line without cutting the pipe or moving the end connections. On titanium lines that matters, because a valve is usually the cheapest part of a welded assembly and the most likely to need new seats. This body style is made in Grade 1 and Grade 2 to ASME B16.34, with full port bore and a floating ball.

How the Three-Piece Body Is Built

The assembly is a centre body, a ball with a full bore, two seats and two threaded or welded end caps drawn together by four through bolts. Removing those bolts lets the centre swing clear while the end caps stay on the pipe, so seats, seals and the ball itself can be replaced in place. Body wall thickness follows ASME B16.34 for the chosen class, and the end caps are machined from the same grade as the centre so that galvanic effects across the joint do not arise.

Valve Specification

Grade 1 or Grade 2 - Which to Specify

Grade 1 is the softer commercially pure grade, with a minimum tensile strength of 240 MPa and the highest ductility and formability of the family. It suits low pressure water, seawater and mildly oxidising chemical service where the priority is corrosion life and easy welding. Grade 2 raises the minimum tensile strength to 345 MPa with 275 MPa yield and is the usual choice for Class 300 bodies, larger sizes and lines that see water hammer or thermal cycling. Both grades remain non magnetic and are unaffected by chlorinated water at ambient temperature.

Seat Behaviour and Torque

PTFE seats give bubble tight shutoff with a low operating torque, which is why a 4 inch valve can still be turned by hand. Above 180 C the seat material changes to PEEK and the torque rises, so a worm gear or actuator is normally specified from DN80 upward in that version. The stem is blowout proof, located by an anti-static device that keeps the ball, stem and body electrically continuous for service where static charge must not build up.

Testing and Documentation

Every valve is pressure tested to API 598 with a shell test at 1.5 times the rated pressure and a seat test at 1.1 times, both held for the full duration required by the standard, and the test record is filed against the valve serial number. A mill certificate to EN 10204 3.1 for the titanium parts, a dimensional report and a seat test chart are issued with each shipment. Actuated valves are supplied with a mounting pad to ISO 5211 so that a customer supplied actuator can be fitted without an adapter plate.

Product Images