EKINSUN LTD is a custom parts manufacturer that machines bulkhead fittings to drawing: a body long enough for a 12 mm tank wall, a thread the series does not carry on one side, a flange and bolt pattern instead of a jam nut, a bulkhead elbow in 316L, a push-in or compression bulkhead body for a panel the series jam nut cannot reach across, from 1 piece.
A typical request: a 10 mm stainless tank wall where the series bulkhead nut only reaches across 6 mm, G1/2 on the inside and 1/2 NPT on the outside for a US hose.
Panel thickness and a mixed pair: the two commonest reasons a bulkhead is machined.
Bulkhead fitting forms
| Form | Ports | Fixes to the panel by | Range | Where it is used |
|---|---|---|---|---|
| Threaded bulkhead union | F × F through the panel | jam nut on the body thread | G1/8–G1; NPT 1/8–1; metric | tanks, enclosures, machine walls |
| Threaded bulkhead adapter | M × F, or M × M | jam nut | G1/8–G3/4; NPT | a pipe outside and a fitting inside |
| Bulkhead hose barb | barb × F or M through the panel | jam nut | 1/4–3/4 in | a hose on one side of a wall |
| Push-in bulkhead union | tube × tube through the panel | jam nut on the body | 4–16 mm; 1/4–1/2 in tube | pneumatic panels, control cabinets |
| Push-in bulkhead female | tube × F through the panel | jam nut | 4–12 mm tube; G1/8–G3/8 | a threaded connection behind the panel |
| Push-in bulkhead elbow | tube × tube at 90° through the panel | jam nut | 4–12 mm | tight cabinets |
| 24° cone bulkhead union | tube × tube, DIN 2353 | jam nut | 6–42 mm tube | hydraulic and lubrication walls |
| Twin-ferrule bulkhead union | tube × tube | jam nut | 3–25 mm; 1/8–1 in | instrument panels, analysers |
| Tank bulkhead (tank connector) | F × F with a wide flange and gasket | flange nut with gasket | 1/2–2 in | plastic and steel tanks, water and chemical |
| Flanged bulkhead | any, with a bolted flange | bolts through the panel | to drawing | thick walls, pressure vessels, where a nut cannot be reached |
| Weld-in bulkhead | F × F or tube × tube on a weld boss | welded | to drawing | stainless tanks and vessels |
Need bulkhead fittings in a size, thread or material no catalogue lists? EKINSUN is a custom parts manufacturer: we make bulkhead fittings to your drawing, sketch or sample — brass, 304 or 316L stainless steel — from 1 piece, quoted in 12 hours and shipped duties paid. If the size is standard, ask anyway — it may be in stock, and the unit price drops as the quantity rises. All custom adapters and fittings →
The three numbers: hole, thickness, thread
| Number | Where it comes from | What goes wrong |
|---|---|---|
| Panel hole diameter | the body outside diameter plus clearance; the series lists it per size | too small and the body will not pass; too large and the jam nut face does not seat |
| Panel thickness | the length of body thread the jam nut can travel; the series lists a maximum per size | a thicker panel leaves no thread for the nut; the fitting cannot be clamped |
| Port threads | each end's standard and size; the series keeps both the same | a mixed pair or a metric-fine end is not catalogued |
| Sealing to the panel | O-ring or gasket under the head, or a flat face on a machined panel | a wet panel leaks around the body without a seal |
| Orientation | hex on the head, flats on the body for a spanner | a body with no flats spins while the nut is tightened |
A bulkhead is measured on the panel, not on the fitting: hole diameter, panel thickness including paint or gasket, and the space behind the panel for the nut and a spanner. Those three numbers decide whether a series bulkhead fits before any thread is discussed.
What to send for a bulkhead that is not catalogued
- Panel material and thickness, and the hole if it is already cut.
- Each port: male or female, standard, size and pitch; tube outside diameter for push-in or compression ends.
- How it fixes: jam nut, flange with bolts, or weld-in; and the space behind the panel.
- Seal to the panel: O-ring, gasket, none.
- Material: nickel-plated brass, 304, 316L; medium and pressure.
- Quantity; a single bulkhead for a tank that is being repaired is a normal order.
Identify the thread before you order the bulkhead fitting. Measure the outside diameter of a male thread, or the inside diameter at the mouth of a female one, with a caliper, and count the threads in 25 mm or in one inch. A G1/4 male measures about 13.2 mm across and has 19 threads per inch; a 1/4 NPT male measures about 13.7 mm and has 18; an M14×1.5 measures 14.0 mm with 1.5 mm between crests. Those three are the ones most often confused on a fitting, and only the metric one is not tapered. Then check whether the thread is parallel or tapered by measuring the diameter at the first and the fifth turn. The fitting thread identification chart lists every common pipe, port and tube thread with its diameter, pitch and seal, and the BSPP vs BSPT note explains the parallel and taper forms of the same BSP size.
Where the bulkhead catalogue stops
| What you need | In the catalogue? | What we make |
|---|---|---|
| Threaded bulkhead union F × F in G or NPT 1/8–1 in, brass or 304, panel inside the series thickness | Yes | Buy it from stock, or have it made to order from 1 piece; no one-off competes on price with a series bulkhead. Standard parts: ask us too — we may have them in stock. |
| Push-in, 24° cone or twin-ferrule bulkhead union in a series tube size | Yes | Standard sizes: buy it off the shelf, or have the body made to order from 1 piece. Standard parts: ask us too — we may have them in stock. |
| A panel thicker than the series jam nut reaches across | No | Body machined long enough for the panel, with the jam nut thread to match; from 1 piece. |
| Two different ports — G inside and NPT outside, a tube one side and a thread the other, a metric-fine end | No | Machined; each end to its own standard; push-in or compression ends fitted from the series. |
| A hole that is not the series hole, a square or keyed hole, or a flange with a bolt pattern instead of a nut | No | Machined to the hole or the bolt pattern. |
| A bulkhead in 316L, titanium, PEEK or aluminium 6061 / 7075 | No | Same geometry, your material. |
| A bulkhead elbow or tee in a threaded form the series does not carry | No | Machined from hex or square bar. |
| A weld-in bulkhead or a tank connector for a vessel wall | No | Machined with a weld boss or a flange and gasket seat; welding by the tank builder. |
Materials
| Material | Designation | Where it fits here |
|---|---|---|
| Nickel-plated brass | CW614N / C36000 | standard threaded and push-in bulkheads for air and water |
| Stainless 304 | 1.4301 | standard stainless bulkheads; enclosures and washdown panels |
| Stainless 316L | 1.4404 / 1.4571 | machined bulkheads for tanks, marine and chemical walls; twin-ferrule series |
| Free-machining stainless | 303 / 1.4305 | custom turned bodies where corrosion duty allows |
| Carbon steel | zinc or phosphate | 24° cone bulkhead unions |
| Aluminium 6061 | AlMg1SiCu | light bulkheads for air and vacuum panels; also the panel material most enclosures are |
| Aluminium 7075 | AlZn5.5MgCu | machined bulkhead blocks |
| Polypropylene, PVC, PEEK | PP, PVC-U, PEEK | tank connectors and chemical bulkheads |
| Seals | NBR, EPDM, FKM, PTFE | O-rings and gaskets to the panel |
Related pages
- every fitting by port combination — every fitting form by ports and standard
- push-in fittings — push-in bulkheads
- compression fittings — 24° cone and twin-ferrule bulkheads
- Cable gland and conduit adapters — the other part that passes through a panel
- Female-to-female adapters — the union without the panel
- Sealed metal parts — O-ring seats and gasket faces
- Custom enclosures — the panel the bulkhead goes through
Frequently asked questions
A fitting that carries a line through a panel, wall or tank: a long threaded body passes through a hole, a jam nut clamps it from the far side, and each end takes a pipe, tube or hose. Bulkhead unions have the same connection on both ends; bulkhead adapters have different ones.
As thick as the jam nut can travel on the body thread, which the series lists as a maximum per size, typically a few millimetres on small fittings. A thicker panel needs a body machined with a longer thread, or a flanged bulkhead bolted through the panel.
The body outside diameter plus a small clearance, listed per size by the series. The hole must be round and clean so the O-ring or gasket under the head seals; a keyed or square hole, or a non-series diameter, is machined to match.
Not as standard parts: series bulkhead unions keep both ends the same. A G × NPT, tube × thread or metric-fine bulkhead is machined with each end to its own standard, from 1 piece, with push-in or compression ends fitted from the series where a tube is involved.
EKINSUN LTD is a custom parts manufacturer that machines threaded, push-in, compression, flanged and weld-in bulkhead fittings to the panel and ports you specify, in brass, 304 / 316L stainless, steel, aluminium and PEEK, from 1 piece, with a quote within 12 hours.
No list price; the drivers are material, body length, the two end threads or tube ends, a flange if there is one, and quantity. A brass bulkhead body machined longer for a thick panel is a short job; a 316L flanged tank bulkhead with a gasket seat is priced as the machined part it is. The quote states which.
Send the panel and the two ends
Panel thickness and material, hole if cut, each end (thread or tube OD), jam nut or flange, seal, body material, quantity. A photo of the wall with a rule works. From 1 piece, quote within 12 hours.
Not sure of the thread? Tell us four things: what the fitting connects to (pump, valve, gauge, cylinder, tube or hose); whether the port is the inlet or the outlet; which way the flow must go; and the tube outside diameter, not the hose bore, unless it is a barb. A photo with a caliper across the thread answers most of it.