30x30"900LB A105 Large-bore Trunnion Mounted Ball Valve

Overview of the J-VALVES 30x30 Inch 900LB A105 Large Bore Trunnion Mounted Ball Valve

At thirty inches this valve has left the flange table that most buyers keep in their head. ASME B16.5 runs to 24 inches, and above that the flanges come from ASME B16.47, which is a different document with a different set of dimensions. A buyer who specifies a thirty inch Class 900 valve as though it were a scaled up 24 inch one will find that nothing in the joint matches: not the outside diameter, not the bolt circle, and not the length of the studs.

B16.47 makes it one step harder, because it is published in two series. The two series describe the same nominal size and class with different flange dimensions, and both are in use, one largely in North America and one largely elsewhere. A valve can be made to either, but not to both, and the ring gasket and the studs are ordered against the series. So this page is about one decision: which series, and why the answer has to be on the order rather than inferred from the class.

Design and Construction

The valve is a large bore trunnion design, which at DN750 is the only construction that makes sense: the ball is supported on upper and lower trunnions so that the pressure load goes into bearings rather than into the seat, and the operator only turns friction. A floating ball at this diameter would need a seat and an operator that no one would build, and the torque would rise with the pressure rather than staying roughly constant.

The body is a bolted construction, and the trim enters through the body joints rather than through a flange. At this size the joints are large and the gaskets are large, and the assembly has to be done on a bench with the body supported, because a joint that is pulled down on one side will not straighten itself and a leak at this size is a shutdown rather than a weep. The number of joints is stated on the drawing for the body style ordered.

The bore is full, so the passage matches the pipe and a pig or an inspection gauge can pass. That is the point of a full bore valve at this size and it is also why the valve is heavy: the ball is large, the seats are large, and the operator has to move a large mass through ninety degrees. The gear is not an accessory here, it is the operator.

Material Options

The body is A105, a forged carbon steel, which at this size means a very large forging or a set of forged parts rather than a single small block. The material is the ordinary choice for oil, gas and water at ordinary temperature, and the certificate is the document that proves what was supplied. Where the line runs cold, an A350 LF2 forging is the alternative, and where it is corrosive, a stainless grade is, and both are quoted rather than stocked.

The ball is carbon steel with a nickel or chrome deposit, or an alloy overlay where the medium is abrasive. At thirty inches the ball is the most expensive single part after the body, which is why the deposit is inspected rather than assumed: a damaged coating on a ball this size is not a touch up, it is a replacement. The trunnions are the parts that carry it, and their hardness is what keeps the torque from rising as the valve ages.

The seat is PEEK or a metal seat with graphite, because the soft seat family does not reach the temperatures and pressures this valve is bought for. A metal seat is judged on a leakage rate rather than on zero leakage, and the rate has to be agreed at the order, because a thirty inch metal seat that is asked to hold bubble tight will be rejected against a criterion the standard never promised.

Technical Specifications

The class is Class 900, which API 6D writes as PN 150, and the ends are ring type joint to ASME B16.47 in the series ordered. The ring itself is a separate item to ASME B16.20 and it is normally bought with the line rather than with the valve, which is why the series matters so early: a ring bought for the other series will not seat in the groove, and the error is discovered when the joint is made.

Face to face is dimensioned on the signed general arrangement drawing for the build ordered, because at this size the length is a function of the body style and the flange series rather than a single tabulated figure. Weight is quoted with the drawing as well, and it is a real figure rather than an estimate, because the lifting plan, the support and the transport are all designed against it.

The operator is a gear as standard, with pneumatic, hydraulic or gas hydraulic actuation available where the valve is on an emergency shutdown loop. The gear ratio and the handwheel force are quoted with the valve, and the actuator, where fitted, is sized against the measured torque rather than a catalogue figure, because at this size a torque taken from a table for a smaller valve would leave the actuator unable to seat the ball against the seat load.

Standards and Compliance

ASME B16.34 gives the rating and the minimum wall for the forging. ASME B16.47 gives the flange dimensions, and it is the document that makes this valve different from every smaller one in the range. ASME B16.20 gives the ring joint gasket, and API 6D gives the pipeline valve requirements: the functional tests, the marking, the cavity relief and the documentation. Four documents, and the joint depends on three of them at once, which is why the flange series has to be written rather than assumed.

The two series in B16.47 are the reason a class alone is not enough. Both are legitimate, both are in current use, and a flange cut to one will not accept a gasket or a counter flange cut to the other. A purchase order that says Class 900 ring type joint, thirty inch, and nothing else leaves the works to choose, and the works will choose the one it normally makes. That is not a defect in the valve; it is a gap in the order.

API 598 sets the shell test at one and a half times the rating and the seat test at one and one tenth times. At thirty inch the shell test is a large volume of water at pressure and it takes a test bay and a handling plan rather than a bench, which is why the test date is worth agreeing at the order. Where a fire safe design is required, the order names API 607, API 6FA or ISO 10497.

Manufacturing Process

The body and the ends are formed, heat treated and then machined from the flange faces. The flange is faced and drilled to the series that was ordered, and this is the operation where the order either matches the pipe or does not: the same body can be drilled to either series, so the drawing has to carry the series before the flange is touched.

The ring groove is cut in the same setup as the face so that it stays concentric with the bolt circle, and the groove is protected from the first day it exists. Assembly of a valve this size takes a crane and a bench that can hold the body square, and the joints are closed in a cross pattern to the drawing torque with the faces checked for parallel at each step.

Quality Control and Testing

The material certificate is written against the heat number stamped on the body, and at this size the certificate is accompanied by the heat treatment record, because the property that matters on a large forging is as much the treatment as the chemistry. Where the order asks for an ultrasonic examination or a positive material identification report, that is quoted with the order and written against the same heat.

The shell test is run with the body assembled at one and a half times the Class 900 rating, and every joint, the packing and the wall are watched. The seat test follows in both directions at one and one tenth times with the cavity open, and on a metal seat the result is recorded as a rate rather than as a pass or fail, because that is what the standard asks for. After testing the valve is stroked with the gear, the torque is recorded, and the plate is read against the certificate.

Applications and Industry Service

This valve belongs on transmission lines, pump station headers, manifold piping and tank farm main lines, where thirty inch is the line size and Class 900 is the design pressure. It is bought for isolation rather than for control, and it is bought with the pigging requirement in mind, which is why the bore is full and why the passage is checked against the gauge that will run through it.

It is the wrong valve where the line is smaller than the valve, where the pressure class is set by a flange rather than by the process, and where the valve would have to be installed without room for the gear and the lifting equipment. At DN750 the installation is a project in itself, and a valve that fits the pipe but not the space is still the wrong valve.

Installation, Operation and Maintenance

The valve is lifted on the lugs provided and never on the gear or the stem, and it is supported under the body so that the pipe does not carry it. The flanges are brought parallel and the joint is made with the ring for the series that was ordered, dry and clean, with the studs torqued in a cross pattern to the values for the size, class and series. A ring joint at this size is a joint that is made once.

In service the gear is greased on its own schedule and the stem packing is adjusted from the gland. The body joints are opened only for a seat change, and after any break the shell test is repeated, because a body that has been opened is a new pressure boundary and at this size the test is cheaper than the return visit. The cavity vent and drain are used to prove the seats before the line is opened.

How to Specify and Order

The order needs size, class, flange standard and series, ring type joint, body material, bore, seat, operator, gear ratio and test standard. The series is the line that is most often left out and it is the one that cannot be fixed later: write ASME B16.47 and then write A or B, and write it in the same place as the class so that the two are read together.

Two more lines are worth adding at this size: the pig or gauge that has to pass, and the lifting and transport arrangement. Neither changes the valve, and both change whether the valve arrives usable. A drawing that carries the flange series, the face to face, the weight and the lifting points answers every question the site will ask before the valve is on the truck.

FAQ

Q: Why is the flange not ASME B16.5?

A: Because B16.5 stops at 24 inches and this valve is 30. Above that size flanges come from ASME B16.47, which has its own dimensions and its own two series. A thirty inch valve cannot be ordered to B16.5 whatever the drawing says, and a counter flange cut to B16.5 will not fit it. The class is the same idea in both documents; the dimensions are not.

Q: What is the difference between series A and series B?

A: They are two flange dimension sets published in the same standard, both in current use, with different outside diameters and different bolt circles for the same nominal size and class. Series A is the one more common in North American practice and series B in other regions, though both travel. A valve can be made to either, and the gasket and the studs follow the series rather than the class.

Q: What happens if the series is left off the order?

A: The works makes the series it normally makes, and the mismatch is discovered when the joint is assembled: the ring will not sit in the groove or the studs will not pass. At thirty inch that is not a small correction, because the ring gasket, the studs and possibly the counter flange are all wrong together. It is the cheapest line to add to a purchase order and the most expensive one to leave out.

Q: Is the bore always full at this size?

A: For a line that is pigged, yes, and at thirty inch that is the normal requirement. A reduced bore at this size would defeat the purpose of the valve in a transmission line, and it would also make the valve a restriction that the line design has not accounted for. Where the valve is on a branch that is never pigged, a reduced bore is possible, but it is a different body and a different drawing.

Q: Why is a metal seat used rather than PTFE?

A: Because at Class 900 and at the temperatures this valve is bought for, the soft seat family is out of its range. A metal seat with graphite takes the temperature and does not creep, at the cost of a leakage rate that has to be agreed rather than a zero. The rate should be written on the order, because a metal seat judged against a soft seat criterion will never pass.

Q: How is a valve this size tested?

A: On a test bay, with a handling plan, at one and a half times the Class 900 rating for the shell and one and one tenth times for the seat in both directions. Every body joint and the packing are watched, and the valve is stroked with its gear afterwards so that the torque can be recorded. The test occupies the bay for a considerable time, which is why the date is worth agreeing early.