Bulkhead Union Manufacturer, Supplier & Exporter
A bulkhead union carries a tube connection through a panel, enclosure wall or bulkhead. It has a long threaded body that passes through a hole in the panel and is clamped in place with a locknut, with a tube compression end on each side. Raaj Fittings manufactures and exports bulkhead unions and bulkhead connectors in double ferrule and single ferrule designs, in SS 316L, SS 304, duplex, super duplex and nickel alloys.
Bulkhead fittings give a neat, rigid entry point where tubing enters or leaves an instrument enclosure, junction box, gas cabinet or analyser shelter. The tube on each side can be disconnected independently, so equipment inside the panel can be serviced without disturbing the field tubing.
All bulkhead fittings are supplied with EN 10204 3.1 mill test certificates and full material traceability.
We export bulkhead unions to instrumentation contractors, OEMs and distributors across the Middle East and GCC, Europe and the Americas, in metric and imperial tube sizes with NPT or BSP ends to suit each market.
Bulkhead Union Specifications
Metric 3–25 mm; imperial 1/8"–1"
Bulkhead union (tube × tube), bulkhead male connector and bulkhead female connector
Double ferrule and single ferrule compression
Through-panel body with hex shoulder and locknut; panel hole size and maximum panel thickness to the fitting data
Double ferrule up to 413 bar (6,000 psi); single ferrule up to 207 bar (3,000 psi), depending on size and material
Precision-machined from bar stock
EN 10204 3.1 mill test certificate; EN 10204 3.2 on request
Materials & Grades
We supply bulkhead unions in the following materials and grades. All grades are supplied with EN 10204 3.1 / 3.2 Mill Test Certificates.
Stainless Steel Bulkhead Unions
Stainless steel is the standard material for instrumentation tube fittings across oil and gas, petrochemical, pharmaceutical, and offshore applications. SS 316L is the most widely specified grade.
The industry default for instrumentation tube fittings — low carbon content prevents sensitisation; molybdenum addition provides superior chloride and acid resistance versus 304 grades.
Superior chloride and acid resistance — used where chloride exposure, marine atmosphere, or mild chemical service requires better corrosion resistance than 304.
General corrosion resistance at lower cost than 316L — suitable for water, steam, mild chemical, and food-grade applications where chloride exposure is limited.
Duplex & Super Duplex Stainless Steel Bulkhead Unions
Duplex and super duplex grades provide approximately twice the yield strength of 316L with excellent resistance to chloride stress corrosion cracking — the preferred choice for offshore and subsea instrumentation where standard 316L may be susceptible to SCC.
(UNS S31803 / S32205) Offshore topsides instrumentation, seawater injection, and chemical injection systems
(UNS S32750) Subsea instrumentation, high-chloride offshore service, and FPSOs — PREN ≥ 42
Nickel Alloy Bulkhead Unions
For aggressive chemical, sour gas, and high-temperature service where duplex stainless steel is insufficient — specified in chemical injection, downhole instrumentation, and severe process environments.
(UNS N06625) Outstanding corrosion resistance in offshore, subsea, and chemical service; widely specified for downhole instrumentation and subsea chemical injection tubing
(UNS N10276) Broad-spectrum resistance to aggressive acids, chlorides, and oxidising media; chemical and FGD process sample systems
(UNS N04400) Hydrofluoric acid service, seawater, and marine instrumentation systems
(UNS N08020) Sulfuric acid and aggressive chemical process sample and instrumentation systems
Special Grades & High-Purity Bulkhead Unions
For semiconductor, pharmaceutical, and high-purity gas applications requiring electropolished internal surfaces and ultra-low extractable contamination.
Pharmaceutical and biotech grade — electropolished internal surface for sterile process piping, pure steam, WFI, and clean compressed air systems in GMP-compliant facilities.
Semiconductor grade — ultra-high-purity electropolished finish for process gas delivery, specialty gas distribution, and wet chemistry in semiconductor fabs.
Exceptional corrosion resistance in seawater and oxidising media at low density — used in desalination and marine instrumentation where weight is a factor.
How a Bulkhead Union Is Fitted
A hole of the specified size is drilled or punched in the panel. The bulkhead body is pushed through until its hex shoulder sits against one side, and the locknut is tightened on the other side to clamp the panel. Tubes are then connected to each end with standard compression nuts and ferrules.
- Clean panel entry — a tidy, rigid penetration for each tube.
- Independent connections — inside and outside tubes can be removed separately.
- Supports the tube — the panel takes the load at the entry point.
- Fewer separate fittings — no need for a gland plus a union.
Bulkhead Union or Bulkhead Connector?
A bulkhead union has tube ends on both sides of the panel. A bulkhead male or female connector has a tube end on one side and a threaded end on the other, for connecting directly to a threaded component mounted at the panel wall. Choose the type that matches the equipment layout inside the enclosure. Standard union connectors and female connectors complete the tubing inside and outside the panel.
Weatherproofing
For outdoor analyser shelters and enclosures, a suitable sealing washer or gasket under the shoulder helps keep water and dust out. Confirm the panel thickness when ordering so the threaded length suits the wall and any sealing washer.
Applications & Industries
- Analyser shelters and sample conditioning cabinets
- Instrument enclosures and junction boxes
- Gas cabinets and calibration panels
- Control panels for hydraulic and pneumatic systems
- Offshore instrument and control enclosures
Bulkhead fittings are usually ordered in sets for each enclosure, matched to the number of tube entries shown on the panel layout drawing. Supplying them in the same material and fitting design as the field tubing keeps every joint compatible and simplifies spares. For analyser shelters with many entries, a common bulkhead plate is often drilled to a grid so that all tubes enter at one tidy, labelled location.
When ordering, give the tube OD, bulkhead type, fitting design, panel thickness and material grade. See all tube fittings.
Testing, Inspection, Marking & Packing
Bulkhead fittings are produced under our quality assurance process:
- Bar stock verified by PMI testing, with full traceability
- Dimensional inspection of body threads, locknut, seats and hex sizes
- Pressure testing on request
- Marking with material grade and heat code
Supplied with EN 10204 3.1 mill test certificates; EN 10204 3.2 certificates and third-party inspection on request.
Fittings are capped and bagged to keep ports clean, then boxed and packed in seaworthy wooden cases for export; marking, tagging and packing to your specification are available on request.
Why Choose Raaj Fittings for Bulkhead Unions?
Raaj Sagar Steels has supplied piping components since 2003 and today manufactures tube fittings at two plants in India for buyers in the Middle East, Europe and the Americas.
- Manufactured in-house — Bulkhead unions are made in our own plants, so material, dimensions and delivery stay under our control.
- Ready stock, short lead times — common sizes and grades are held in stock for prompt dispatch; other sizes, grades and specials are manufactured to order.
- Certified quality — ISO 9001:2015, ISO 14001:2015 and ISO 45001:2018 certified; PED 2014/68/EU supply available, and NACE MR0175 / ISO 15156 material on request.
- 100% material verification — PMI testing on incoming material and EN 10204 3.1 mill test certificates with every order; 3.2 certificates on request.
- Third-party inspection ready — we regularly work with SGS, Bureau Veritas, TÜV and DNV.
- Export documentation — MTCs, certificates of origin, packing lists and inspection reports to suit projects in the GCC, Europe and the Americas.
- Export packing — seaworthy packing with end and face protection, and packing to your specification on request.
- Fast response — our team replies to enquiries within one business day.
Bulkhead Unions — FAQs
A bulkhead union is a tube fitting that passes through a panel or wall and is held by a locknut, with a tube compression end on each side.
Where tubing enters or leaves an instrument enclosure, junction box, gas cabinet or analyser shelter.
A bulkhead union has tube ends on both sides. A bulkhead connector has a tube end on one side and a male or female thread on the other.
The tube OD, bulkhead type, fitting design, material grade and the thickness of the panel the fitting will pass through.
Yes. A sealing washer or gasket under the shoulder or locknut helps keep water and dust out of outdoor enclosures.
Yes. We supply bulkhead unions for projects under the European Pressure Equipment Directive (PED 2014/68/EU), with EN 10204 3.1 certificates as standard and 3.2 on request. NACE MR0175 / ISO 15156 compliant material is available for sour service in the Middle East and the Americas.
