1 Inch PN100 F304 Three Piece Floating Ball Valve

Overview of the J-VALVES 1 Inch PN100 F304 Floating Ball Valve

This is a one inch valve: DN25 nominal bore, PN100 pressure designation, which is the same step as Class 600. The body is ASTM A182 F304 forged austenitic stainless steel, built as three bolted pieces, and the ends are NPT thread to ASME B1.20.1, socket weld to ASME B16.11 or butt weld to ASME B16.25. The ball floats between two seat rings, the operator is a lever with a locking device, and the test is API 598.

The word forged on this page needs one sentence of care, because the original page gets it wrong. It says the body is machined from a single forging, an integral one piece body. The photograph shows four bolts holding two end caps onto a centre section, so the body is three pieces and cannot be a single forging. What is forged is each of those three pieces: they start as A182 F304 forgings rather than castings, which is where the grain structure and the pressure capacity come from.

One inch high pressure is its own product rather than a small version of a six inch valve. On an instrument line, a sampling point or a chemical injection skid, the valve is the cheapest item in the assembly and the only one that stops the plant when it leaks. That is why this size is bought in F304 rather than carbon steel, why the ends are welded or threaded instead of flanged, and why the body is bolted so the seats can be changed without cutting the tube.

Design and Construction

In a floating design the ball is not carried on trunnions. It sits between two seat rings with a little room to move, and the line pressure acting on the upstream half of the ball pushes the whole ball downstream until it presses on the outlet seat. The seal is produced by the pressure itself, so it tightens as the pressure rises. The force that has to be overcome to turn the valve comes from the same source, which is why a floating valve gets harder to operate as the bore grows.

At DN25 the arithmetic stays friendly. The area the pressure acts on is small, so even at Class 600 the seat load and the breakaway torque remain inside what a hand lever can supply, and the valve does not need a gearbox or a trunnion to hold the ball. This is the size band where the floating design is not a compromise but the better answer: fewer parts, one sealing face, nothing to lubricate and nothing to maintain between services.

The three piece body is bolted through four fasteners, and the joint between the centre section and each end cap is closed on a gasket. That joint is the part to respect: it is a pressure boundary that a fitter can open, so it has to be closed to the specified bolt load and with a new gasket every time. In exchange, the ball and both seats come out from either end with the valve still in the line, which on a welded instrument run is the difference between an hour and a day.

The stem enters from the top through the gland, is retained by the body so that it cannot be blown out, and drives the ball through a slot. An anti static path runs from the ball through the stem to the body so that charge cannot build up across the seat. On top of the bonnet there is a square mounting pad with four tapped holes, which is where a miniature pneumatic or electric actuator mounts when the valve stops being hand operated.

Material Options

F304 is the body material on this page: forged austenitic stainless, 18 chromium and 8 nickel, non magnetic, tough at low temperature and resistant to atmospheric and fresh water corrosion. It is the right default for water, oil, gas, instrument air and most neutral chemicals. F304L is offered where the ends will be welded, because the lower carbon avoids sensitisation in the heat affected zone, and F316 or F316L where the medium carries chlorides and pitting resistance matters.

The trim follows the body. The ball is solid F304, either bare or with electroless nickel plating, and hard chrome is available where the medium is slightly abrasive. The stem is F304 or F316, with 17-4PH precipitation hardening stainless where the torque is high or the duty is frequent. The seat is the part that actually sets the temperature limit, and it is ordered as PTFE, RPTFE, PPL or a metal seat with flexible graphite, in that order of rising temperature.

Technical Specifications

The envelope is DN25, PN100 or Class 600, three piece bolted body in forged F304, ends in thread, socket weld or butt weld, lever with locking device, and a test to API 598. Because the ends are not flanged, the end to end length is the one on the signed drawing rather than a tabulated figure; where the same valve is ordered with flanges, the length follows ASME B16.10. The numbers that ship are the ones confirmed on that drawing for the size and trim ordered.

Two choices decide whether this valve is right. The first is the end preparation, because a threaded valve and a butt weld valve are not interchangeable once the pipe is in place. The second is the seat compound, because the body can take far more temperature than any polymer seat can, and the valve is only as good as the soft part inside it. Both belong in the enquiry, not in a later phone call.

Standards and Compliance

ASME B16.34 sets the wall thickness and the pressure temperature rating. F304 is an austenitic stainless steel, which B16.34 places in material group 3.1: the rating table runs from minus 254 to plus 538 degrees Celsius, and Class 600 corresponds to 102.1 bar at 38 degrees. API 608 covers the ball valve specifics that B16.34 does not: the anti static path, the blowout proof stem, and what the nameplate has to carry.

PN100 and Class 600 are two names for the same step, and API 6D lists PN100 against Class 600 in its pressure designation table, so the original page is right to write them together. One warning is worth keeping: PN100 is also a flange designation under EN 1092-1, and a PN100 flange does not share a bolt circle with an ASME B16.5 Class 600 flange. On this valve the ends are threaded or welded, so PN100 here is a rating label and nothing more. Fire safety is to API 607 where it is ordered.

Manufacturing Process

Each of the three body parts starts as an A182 F304 forging, is solution annealed, and is then machined. The seat pocket, the joint face and the bore are cut in the same setting so that the seat ring sits square to the ball axis, because a seat pocket that is a few hundredths out of square shows up later as a leak that no amount of bolt torque will cure.

The ball is machined, ground and lapped, then plated where plating is ordered. The stem is machined with the anti static recess and the drive slot, and the gland thread is cut to take the packing load. Assembly is seats into the centre section and the end caps, ball between them, gaskets on both joints, then the four bolts taken up in a cross pattern to the specified torque, and finally the packing compressed and the lever fitted.

Quality Control and Testing

Every valve is shell tested at one and a half times the rating and seat tested at one point one times, both to API 598. The seat test is run in both directions, and on a floating valve that matters more than it looks: only the downstream seat seals, so the upstream seat is proven on reverse flow. A valve tested in one direction only can pass on the bench and still leak the first time the line is back pressured from the other side.

The rest of the record is dimensional and material. The thread is gauged to ASME B1.20.1, the socket to ASME B16.11, the butt weld end to ASME B16.25, the bore checked for full port, and the heat number on the certificate checked against the marking. Torque is measured on the assembled valve and issued with the drawing, which is the figure an actuator has to be sized on.

Applications and Industry Service

The duty is small bore isolation on lines where the pressure is high and the flow is small: chemical injection points, sample and analyser systems, instrument air and nitrogen headers, hydraulic power units, pilot plants and test rigs. In most of those the valve is one of twenty on a skid, bought against a project specification, and the specification will name the body grade, the end type and the seat rather than leave them open.

It is not the right valve for slurry, for throttling, or for a line that swings in temperature often enough to work a polymer seat loose. Where the medium is dirty, a metal seated valve or a different valve type is the better answer; where the duty is throttling, a ball valve of any design is the wrong instrument. Written down plainly, that saves more money than any discount.

Installation, Operation and Maintenance

On a threaded end, use a sealant that is compatible with the medium and do not rely on the thread to carry the load: the pipe has to be supported so that the valve body is not the support. On a socket weld end, the weld heat is the risk, because the PTFE seat is a few centimetres away; weld with the seat and ball removed or with a heat sink on the body, and never quench the weld with water while the valve is assembled.

Operate the valve a quarter turn, fully open or fully closed. Part open, the seat edge sits in the flow and erodes, and on a small bore line the velocity is high enough to do that quickly. If the lever becomes stiff, do not fit a longer handle: on this valve that usually means a deposit on the ball or a swollen seat, and the answer is to open the body and look, not to add force.

How to Specify and Order

State the size, the pressure designation, the body grade, the ball and seat trim, the end preparation and the operator. A typical line reads: one inch, PN100, body A182 F304, ball F304 with ENP, RPTFE seat, NPT female ends to ASME B1.20.1, lever with locking device. If the line is welded, say socket weld to ASME B16.11 or butt weld to ASME B16.25 instead, because the end preparation changes the machining and cannot be added later.

Send the medium, the design pressure and temperature, and whether the valve will be actuated. The medium decides the body grade and the seat; the temperature decides the seat alone; the actuation decides whether the pad and stem top are machined for a drive. A valve ordered without the pad cannot be actuated later without changing the bonnet, which on a one inch valve costs more than the valve did.

FAQ

Q: Is PN100 the same as Class 600?

A: As a pressure designation, yes. API 6D lists PN100 against Class 600, and Class 600 corresponds to 102.1 bar at 38 degrees. The two are not interchangeable as flanges, however: PN100 under EN 1092-1 and Class 600 under ASME B16.5 have different bolt circles. This valve has threaded or welded ends, so the designation is a rating label and the ends are what the pipe has to match.

Q: Is the body forged or cast?

A: Forged, three pieces. Each of the three body parts is machined from an A182 F304 forging rather than cast, which is what gives the tighter grain structure and the pressure capacity. It is not one integral forging: the photograph shows two end caps bolted to a centre section, and that is deliberate, because it lets the seats be changed with the valve still welded in the line.

Q: Why choose a three piece body at this size?

A: Because the seats can be replaced in place. On a one inch line the valve is often welded or threaded into a run that is not worth cutting, and a three piece body lets the centre come out with the pipe ends left alone. A two piece body only opens from one end, so one seat is reachable and the other is not, which is the difference that matters at maintenance time.

Q: What temperature can this valve take?

A: The body is group 3.1 austenitic stainless and the B16.34 rating table runs from minus 254 to plus 538 degrees, but the valve will never see that range because the seat is inside it. A PTFE seat is good to about 150 degrees, RPTFE to about 180, PPL to about 280, and a metal seat with flexible graphite goes to the body limit. The seat compound decides, so it belongs in the order.

Q: Can it be actuated?

A: Yes. There is a square pad with four tapped holes on the bonnet and a stem top machined to take a drive, so a miniature pneumatic or electric actuator mounts directly. Order it as a build rather than adding it later: the pad and the stem top have to be machined for the drive, and a valve supplied without them cannot be converted without changing the bonnet.

Q: Will one inch float, or does it need a trunnion?

A: At DN25 the floating design is the better one. The pressure acts on a small ball area, so the seat load and the breakaway torque stay inside what a lever can supply even at Class 600, and the pressure assisted seal gets tighter as the pressure rises. A trunnion becomes the right answer when the bore grows, the class rises, or the valve is cycled often enough that seat wear matters.