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Service in place · weld ends3‑piece ball valve, SS316, full bore
Two end caps and a bolted centre body. The end caps stay threaded or welded into the pipe while the centre lifts out — so it prevents a line shutdown if maintenance is required. Full bore, 1000 PSI, and the only variant here offered with socket weld and butt weld ends as well as BSPP and NPT.
What a three‑piece ball valve is
Two end caps and a body. The end caps never leave the pipe.
A three‑piece low pressure ball valve comprises three pieces: two end caps and a body, held together by bolts. The end caps are threaded, welded or flanged to connect to the pipe on both sides. Valves with this construction are specifically designed to separate the connection portions of the valve assembly from the rest of the body of the valve.
That separation is the entire point, and it has one consequence worth paying for. Because the end caps stay attached to the pipework, the centre body section can be unbolted and lifted out while the pipe stays where it is. So the three‑piece prevents a line shutdown if maintenance is required — you re‑seat the valve without breaking the pipe run, draining a system or cutting a weld.
- The only variant here with weld ends. Threaded BSPP and NPT, plus socket weld and a separate butt weld range. Nothing else on this range is offered welded.
- Weld ends and a serviceable valve, together. On a two‑piece, welding the valve in means you can never take it out without cutting. On a three‑piece the weld is on the end cap, and the centre still comes out. That combination is why the design exists.
- Full bore. Bore equals the nominal DN at every size — 15 mm at 1/2", 25 mm at 1", 50 mm at 2". Compared to reduced bore.
- More bolted joints than the others. Two body joints instead of one, which is the trade for the access. They are gasketed, designed joints — but if you want the fewest possible sealing surfaces, that is the one‑piece.
- Also the one with a PCD. The dimension tables publish a bolt pitch circle diameter, because the body is bolted — useful if you are checking clearance for a socket or a torque wrench.
Specification
Everything that goes on a purchase order.
| Size range | 1/4" to 4" (DN8 to DN100) threaded · 3/8" to 4" butt weld |
| Body construction | Three piece — two end caps and a bolted centre body. Serviceable in the line |
| Bore | Full bore — the ball hole matches the pipeline |
| Body material | Stainless steel SS316, with CF8M where the part is cast |
| Working pressure | 1000 PSI cold — derate for temperature |
| Working temperature | −29 °C to 150 °C |
| Connection types | Threaded BSPP · NPT · socket weld · butt weld — the only variant here offered welded |
| Seat and seals | PTFE seat, seal, stem seal and packing |
| Ball and stem | SS316, on SS304 body bolts |
| Operation | Quarter turn manual lever |
| Key benefit | Prevents a line shutdown when maintenance is required — the end caps stay in the pipe |
| Stock | Held in Malaysia or Singapore |
Bill of materials and sectional drawings
All 14 parts and what each is made of.
| No | Part name | Material |
|---|---|---|
| 1 | Body | SS316 and CF8M |
| 2 | Cap | SS316 |
| 3 | Ball | SS316 |
| 4 | Seal | PTFE |
| 5 | Bolt | SS304 |
| 6 | Gasket | SS301 |
| 7 | Stem Nut | SS304 |
| 8 | Stem Seal | PTFE |
| 9 | Stem | SS316 |
| 10 | Packing | PTFE |
| 11 | Packing Gland | SS304 |
| 12 | Handle | SS201 |
| 13 | Spring Washer | SS301 |
| 14 | Stem Nut | SS304 |
The manufacturer’s sectional drawings — one per end type. The callout numbers correspond to the part numbers in the table above.
- The bolt and gasket are what make it a three‑piece. SS304 bolts and an SS301 gasket appear in this list and not in the one‑piece or two‑piece lists — they are the parts that hold the two end caps onto the centre body, and the parts you undo to service it.
- Everything wetted is still SS316 or PTFE. Body, cap, ball and stem in SS316; seat, seal, stem seal and packing in PTFE. Same trim as the other two constructions.
- ⚠ The catalogue lists “stem nut” twice, at items 7 and 14. We publish the list as printed rather than silently deduplicating it — there may genuinely be two, or it may be a repetition in the source. Ask us if the exact count matters for a spares order.
- The manufacturer also prints a shorter generic list for this valve, identical to the one‑piece and two‑piece. The list above is the three‑piece specific one, which is the one that includes the bolts.
- The PTFE seat sets the temperature ceiling, not the stainless — hence 150 °C. The derating curve.
Threaded and socket weld — sizes and dimensions
33 rows as published, across BSPP, NPT and socket weld.
Dimensions in millimetres. d is the bore through the ball, L face‑to‑face, H the height from the pipe centreline, E the handle length, and PCD the bolt pitch circle diameter. Rows are left grouped by connection type exactly as the manufacturer publishes them.
| Size | Connection | Bore d | Length L | Height H | Handle E | PCD | Weight (kg) |
|---|---|---|---|---|---|---|---|
| 1/4" | BSPP | 10 | 66 | 45 | 100 | – | 0.30 |
| 3/8" | BSPP | 12 | 66 | 45 | 100 | – | 0.30 |
| 1/2" | BSPP | 15 | 73 | 53 | 104 | 33 | 0.51 |
| 3/4" | BSPP | 20 | 79.5 | 58 | 118 | 39.5 | 0.73 |
| 1" | BSPP | 25 | 86.5 | 68 | 145 | 43.5 | 0.91 |
| 1 1/4" | BSPP | 32 | 108 | 81 | 162 | 55.5 | 1.56 |
| 1 1/2" | BSPP | 38 | 118 | 85 | 180 | 60 | 1.86 |
| 2" | BSPP | 50 | 144 | 92 | 180 | 75 | 2.98 |
| 2 1/2" | BSPP | 65 | 180 | 115 | 242 | 94 | 6.65 |
| 3" | BSPP | 80 | 209 | 130 | 242 | 100 | 10.07 |
| 4" | BSPP | – | – | – | – | 123 | 17.79 |
| 1/4" | NPT | 10 | 66 | 45 | 100 | – | 0.30 |
| 3/8" | NPT | 12 | 66 | 45 | 100 | – | 0.30 |
| 1/2" | NPT | 15 | 73 | 53 | 104 | 33 | 0.51 |
| 3/4" | NPT | 20 | 79.5 | 58 | 118 | 39.5 | 0.73 |
| 1" | NPT | 25 | 86.5 | 68 | 145 | 43.5 | 0.91 |
| 1 1/4" | NPT | 32 | 108 | 81 | 162 | 55.5 | 1.56 |
| 1 1/2" | NPT | 38 | 118 | 85 | 180 | 60 | 1.86 |
| 2" | NPT | 50 | 144 | 92 | 180 | 75 | 2.98 |
| 2 1/2" | NPT | 65 | 180 | 115 | 224 | 94 | 6.65 |
| 3" | NPT | 80 | 209 | 130 | 242 | 100 | 10.07 |
| 4" | NPT | – | – | – | – | 123 | 17.79 |
| 1/4" | SW | 10 | 66 | 45 | 100 | – | 0.30 |
| 3/8" | SW | 12 | 66 | 45 | 100 | – | 0.30 |
| 1/2" | SW | 15 | 73 | 53 | 104 | 33 | 0.51 |
| 3/4" | SW | 20 | 79.5 | 58 | 118 | 39.5 | 0.73 |
| 1" | SW | 25 | 86.5 | 68 | 145 | 43.5 | 0.91 |
| 1 1/4" | SW | 32 | 108 | 81 | 162 | 55.5 | 1.55 |
| 1 1/2" | SW | 38 | 118 | 85 | 180 | 60 | 1.85 |
| 2" | SW | 50 | 144 | 92 | 180 | 75 | 2.98 |
| 2 1/2" | SW | 65 | 180 | 115 | 224 | 94 | 3.54 |
| 3" | SW | 80 | 209 | 130 | 242 | 100 | 6.38 |
| 4" | SW | – | – | – | – | 123 | – |
- Part numbers for the threaded sizes are confirmed per order. The butt weld table below carries its codes in full (VL‑S‑B3‑); for the threaded valve, state the size and end type on your enquiry and we confirm the order code with the factory before anything ships.
- Socket weld rows carry different weights above 2 1/2". At 2 1/2" the published weight is 6.65 kg threaded against 3.54 kg socket weld, and at 3" it is 10.07 against 6.38. Those gaps are too large to be rounding — read the row for the end type you are actually buying.
- Handle length E differs at 2 1/2" too — 242 mm on BSPP against 224 mm on NPT and socket weld. Check it if the valve is going somewhere tight.
- The bore matches the pipe at every size. That is what makes it full bore, and it is the practical difference from the one‑piece.
Butt weld — sizes and dimensions
10 sizes, 3/8" to 4", with part numbers we can stand behind.
The butt weld range is published separately, and its part numbers are internally consistent — the VL‑S‑B3‑BW‑ prefix correctly identifies a three‑piece butt weld valve. W here is the weld end width rather than a handle dimension.
| Size | Part no | Bore d | Length L | Height H | Width W | PCD | Weight (kg) |
|---|---|---|---|---|---|---|---|
| 3/8" | VL-S-B3-BW-1000-06 | 12.5 | 66 | 45 | – | – | – |
| 1/2" | VL-S-B3-BW-1000-08 | 15 | 74 | 50 | 26 | 33 | 0.57 |
| 3/4" | VL-S-B3-BW-1000-12 | 20 | 79 | 60 | 30.5 | 39.5 | 0.51 |
| 1" | VL-S-B3-BW-1000-16 | 25 | 88 | 65 | 36 | 43.5 | 0.73 |
| 1 1/4" | VL-S-B3-BW-1000-20 | 32 | 108 | 85 | 48 | 55.5 | 0.91 |
| 1 1/2" | VL-S-B3-BW-1000-24 | 38 | 119 | 85 | 54 | 60 | 1.56 |
| 2" | VL-S-B3-BW-1000-32 | 49 | 143 | 95 | 68 | 75 | 1.86 |
| 2 1/2" | VL-S-B3-BW-1000-40 | 65 | 180 | 92 | 86 | 94 | – |
| 3" | VL-S-B3-BW-1000-48 | 78 | 209 | 130 | 100 | 100 | – |
| 4" | VL-S-B3-BW-1000-64 | 98 | 260 | 157 | 121 | 123 | – |
- Butt weld starts at 3/8", not 1/4". The threaded range runs from 1/4"; butt weld from 3/8". If you need 1/4" welded, ask about socket weld instead.
- The bores run slightly larger than the threaded range at the top. 4" is 98 mm here against 4" threaded, and 3" is 78 mm — because a butt weld end has no thread eating into the wall.
- ⚠ Some weights are not published. 3/8", 2 1/2", 3" and 4" show no figure in the source. We have left them blank rather than estimate them — ask us and we will weigh one.
- Welding in a three‑piece is not a one‑way decision. The weld is on the end cap, so the centre section still lifts out for service. That is the combination you are buying.
- PCD is published for every size from 1/2" up, so you can check bolt access before the valve arrives.
Pressure–temperature rating
1000 PSI is the cold figure. Here is the curve, and the same curve as numbers.
This valve is used in service from −29 °C to 150 °C, and the environment temperature affects the working pressure across that range. The limit is set by the PTFE seat, not by the stainless body — SS316 is untroubled by 150 °C, but PTFE softens as it warms and the seat is the part holding the pressure.
Read off that curve and interpolated along its straight section. Treat these as approximate figures for selection and ask us to confirm any duty close to the limit.
| Temperature | Working pressure | Approx. PSI | Share of the cold rating |
|---|---|---|---|
| −30 to +20 °C | 63 bar | 914 PSI | 100% |
| 40 °C | 59.8 bar | 867 PSI | 95% |
| 60 °C | 56.5 bar | 819 PSI | 90% |
| 80 °C | 53.3 bar | 773 PSI | 85% |
| 100 °C | 50.1 bar | 727 PSI | 80% |
| 120 °C | 46.8 bar | 679 PSI | 74% |
| 140 °C | 43.6 bar | 632 PSI | 69% |
| 150 °C | 42 bar | 609 PSI | 67% |
- ⚠ A third of the rating is gone by 150 °C. 63 bar cold, 42 bar hot — 67%. If you sized on the catalogue figure and the line runs warm, the margin you thought you had is not there.
- Nothing is lost below about 20 °C. The curve is flat from −30 °C, so ambient and chilled service get the full rating. Derating only begins once the line is warm.
- ⚠ 150 °C is a wall, not a taper. The curve drops vertically to zero there. Do not design a small margin beyond it.
- Rated to the catalogue figures, with the derating curve drawn to 63 bar. For duty near the limit, give us the pressure and temperature together and we confirm against the specific part number.
- The same curve governs the whole stainless range, because it is the PTFE seat that limits, and every stainless variant here uses the same seat material. The range‑wide view.
Not sure this is the right one?
It is the most capable of the three, and the most expensive.
Choose the three‑piece when
- The line cannot be shut down for valve maintenance.
- You want weld ends — socket or butt — and still want to service the valve later.
- The valve is in a hard‑to‑reach or welded‑in position where removing it would be expensive.
- You need full bore and expect to re‑seat it during its life.
Choose something else when
- The line can be stopped for service → two‑piece, same full bore, lower cost.
- You need 2000 PSI → two‑piece; there is no 2000 PSI three‑piece.
- The valve will never be opened → one‑piece, fewest leak paths and cheapest.
- You need to divert or mix → L‑port or T‑port.
- Water or air at modest pressure → brass, at 300 PSI.
- You need 1/8" or a compact body → SS316 mini or brass mini.
All eight, side by side: the comparison table. Other variants: 1‑piece · 2‑piece · L‑port · T‑port · Brass · Brass mini · SS316 mini.
Questions we get asked
The ones that come up on the phone.
What is a 3 piece ball valve?
A ball valve that comprises three pieces: two end caps and a body, bolted together. The end caps are threaded, welded or flanged to connect to the pipe on both sides, and the design separates the connection portions of the valve assembly from the rest of the body. That means the centre section can be removed for service while the end caps stay in the pipework.
Why choose a 3 piece over a 2 piece ball valve?
One reason, and it is usually decisive: the three‑piece prevents a line shutdown if maintenance is required. Both are full bore and both can be re‑seated, but a two‑piece has to come out of the pipe to be opened. On a three‑piece the end caps stay put. It is also the only variant offered with weld ends. It costs more; one avoided shutdown normally covers the difference.
Can I service a 3 piece ball valve without removing it from the line?
Yes — that is what it is for. Undo the body bolts and the centre section lifts out while both end caps remain threaded or welded to the pipe. The pipe run is never broken, so there is no need to cut a weld, re‑make a thread or drain a system to replace a seat. Depressurise and drain the section first, as you would for any valve work.
Do you supply 3 piece ball valves with weld ends?
Yes, and this is the only variant in the range that is. There is socket weld within the main size table and a separate butt weld range from 3/8" to 4", alongside threaded BSPP and NPT. Because the weld is on the end cap rather than the valve body, welding it in does not stop you servicing it later. The butt weld table.
Why are the part numbers missing from the threaded size table?
They are confirmed per order. The butt weld table carries its codes in full (VL‑S‑B3‑); for the threaded valve, state the size and end type on your enquiry and we confirm the order code with the factory before anything ships.
Is a 3 piece ball valve full bore?
Yes. The bore through the ball equals the nominal pipe bore at every size — 15 mm at 1/2", 25 mm at 1", 50 mm at 2" — so the valve does not restrict an open line. Same as the two‑piece; the one‑piece is always reduced bore. The comparison.
How many body joints does it have?
Two — one at each end cap — against one on a two‑piece and none on a one‑piece. They are gasketed, bolted joints and they are not a weakness in normal service, but it is the honest trade: more access means more sealing surfaces. If minimising leak paths is the priority above all else, the one‑piece is a single casting.
What pressure and temperature does it take?
What are the internal parts made of?
SS316 body, cap, ball and stem (CF8M where cast); PTFE seat, seal, stem seal and packing; SS304 body bolts, stem nuts and packing gland; SS301 gasket and spring washer; SS201 handle. The bolts and gasket are the parts unique to this construction. Full list on this page.
Catalogue
Direct PDF download — no form, no email address.
Related: all ball valves · two‑piece if the line can be stopped · Y‑strainers to keep grit off the seat · all low pressure valves.
Tell us the end type and we will confirm the part number
On the threaded range the published part numbers carry the wrong prefix, so we verify the code with the factory before quoting. Send the size, the end type, the pressure and the service temperature. Stock in Malaysia and Singapore.