1BO BSP Male to SAE O-Ring Boss Adaptor, L-Series ISO 11926-3 – 1BO Adapter

The 1BO adapter is a straight hydraulic conversion fitting that joins a BSPP (G thread) port to an SAE O-ring boss (ORB) port in one machined body. Connection 1 is a BSP male stud built for double use: it seals on an ISO 1179 60° cone seat or on a bonded seal against a flat face. Connection 2 is an SAE O-ring boss stud end in the light-duty L series to ISO 11926-3, where an O-ring seals against the flat boss face. HENGHUA cuts both stud ends to the published standards, so each end matches the port it is specified against, which is the precondition for eliminating leakage at the conversion point.

1. What a 1BO Adapter Does

A 1BO adapter connects a BSPP (G) threaded port with an SAE O-ring boss port, or the reverse order of assembly, without changing the direction of flow. It is a rigid straight body, so it is chosen where the two ports already line up and only the port standards differ.

The sealing concepts at the two ends are different and both are face seals. At the BSPP end the stud seats metal to metal on a 60° cone where the port has a cone, or compresses a bonded washer (Dowty-type) against a flat face. At the SAE O-ring boss end the stud carries an O-ring in its undercut, and that O-ring is compressed against the flat face of the boss as the stud nut is tightened, so no cone and no washer are involved at that end.

The SAE end is a straight UNF thread of the light-duty L series to ISO 11926-3, which is why the part numbers in the chart move in sixteenths of an inch on that side, such as 7/16″X20 and 1.1/16″X12. The BSPP end runs from G1/4″X19 to G1.1/2″X11. Each part number therefore represents one fixed pairing, and the O-ring code in the chart identifies the seal that belongs to the SAE end. It is a BSP adapter at one end and an O-ring adapter at the other, and it is supplied as a bonded seal adapter too when the BSPP port has a flat face.

2. 1BO Adapter Specifications

The specification is presented as two mirrored stud ends, so a buyer can read off which end goes to which port before ordering.

2.1 Connection 1 – BSPP male, 60° cone seat or bonded seal

2.2 Connection 2 – SAE O-ring boss male, L series to ISO 11926-3

Note on geometry: the O-ring boss end is a face seal, not a thread seal. The O-ring is captured in the undercut at the base of the thread and seals on the boss face, so the boss face must be flat and free of burrs for the joint to hold. The BSPP end follows ISO 1179, and its 60° cone option corresponds to the cone stud end family covered by ISO 8434-6.

2.3 Construction and Materials

2.4 Pressure and Temperature

Working pressure for this series is governed by the size, the body wall thickness, the sealing method used at each end and the material selected, and it is confirmed per order by HENGHUA engineering against the drawing. No single pressure figure applies to the whole series, so the rating is quoted with the quotation for the specific part number and material.

Seal material temperature ranges are material facts rather than ratings of the assembly: NBR approximately -30°C to +100°C; FKM (Viton-type) approximately -20°C to +200°C; EPDM approximately -40°C to +120°C. Carbon steel with zinc plating suits general hydraulic service; 304 and 316 stainless steel are specified for corrosive and offshore environments. At the SAE O-ring boss end, the O-ring material must be selected for both the fluid and the temperature, because the O-ring is the only sealing element at that joint.

2.5 Part Number and Dimension Table

Column meanings: PART NO. is the ordering code; E is the BSPP (G) stud end; F is the SAE O-ring boss stud end; O-RING F end is the O-ring code for the SAE end; A is the length of the BSPP stud end in mm; B is the length of the SAE stud end in mm; L is the overall length in mm; S1 is the hex across flats in mm.

Table note: every row of the current chart for this series is reproduced above. The chart as supplied ends at 1BO-24, so combinations above G1.1/2″X11 on the BSPP side or above 1.7/8″X12 on the SAE side are quoted on request: [VERIFY WITH SUPPLIER]. All dimensions are in mm and are confirmed against the drawing for the exact part number at order stage.

3. How to Read a 1BO Adapter Part Number

The code has three blocks. 1BO is the series: BSP male double use for 60° seat or bonded seal, with an SAE O-ring boss L-series end to ISO 11926-3. The first number after the prefix is the BSPP (G) size, counted in sixteenths of an inch. The second number, where present, is the SAE O-ring boss nominal size in sixteenths of an inch. When the second number is absent, the two ends are the same nominal fractional size.

Worked example: 1BO-08-12 decodes as 1BO series, 08 = 8/16 in = G1/2″X14 on the BSPP side, 12 = 12/16 in = 1.1/16″ on the SAE O-ring boss side, with the UNF thread shown as 1.1/16″X12 and the O-ring code O912. The chart gives A = 16 mm, B = 15.1 mm, L = 42.5 mm and hex S1 = 36 mm.

Size code reference from the table above: BSPP side 04 = G1/4″X19, 06 = G3/8″X19, 08 = G1/2″X14, 10 = G5/8″X14, 12 = G3/4″X14, 16 = G1″X11, 20 = G1.1/4″X11, 24 = G1.1/2″X11. SAE O-ring boss side 04 = 7/16″X20, 05 = 1/2″X20, 06 = 9/16″X18, 08 = 3/4″X16, 10 = 7/8″X14, 12 = 1.1/16″X12, 14 = 1.3/16″X12, 16 = 1.5/16″X12, 20 = 1.5/8″X12, 24 = 1.7/8″X12.

4. Installation and Fitment

Preparation decides the result because both ends of this series are face seals. Clean both ports, remove old sealant and tape residue, and inspect the boss face at the SAE end and the port face at the BSPP end, since neither an O-ring nor a bonded washer can bridge a scored or dented face. Check that the O-ring supplied matches the code in the chart row, and blow out the line so no swarf reaches the seal faces.

Assembly. Fit the O-ring into the undercut at the base of the SAE stud end and confirm it is seated and not twisted. Fit a bonded washer at the BSPP end if that port is flat-faced. Run the adapter in by hand, then hold the body on the correct hex and tighten the SAE nut against the boss face so the O-ring is compressed but not extruded, followed by the BSPP joint. Never use the hex at one end to jack the other end home, and never apply sealant to the O-ring or the cone seat, because those joints seal on the face or the cone and not on the thread flanks. Torque and tightening angle are confirmed per order and per size by HENGHUA engineering.

Alignment and reuse. Support the hose or tube so the rigid body does not carry bending load. O-rings and bonded washers are single-use items and are replaced whenever a joint is broken; the steel body can be reused if the threads, the O-ring undercut and the cone are undamaged.

Common fitment errors and symptoms: a pinched or twisted O-ring shows as a leak at the boss face that appears as soon as pressure is applied; a missing O-ring is a plain leak along the thread; a damaged or painted boss face lets the joint weep even with a new O-ring; over-tightening does not stop a face seal leak and can shear the O-ring; and a BSPT male end turned into a BSPP port damages both threads, because a taper thread and a parallel thread are not interchangeable.

5. Applications and Industries

Application tags: hydraulic systems, water jetting, oil and gas, industrial equipment, construction machinery, agriculture, marine, material handling.

Cross-standard equipment integration. Mobile and industrial machines built to SAE practice carry O-ring boss ports, while the surrounding plant may be built to BSPP practice, and this series makes the junction at the port rather than at the hose ends.

Repair and replacement. Maintenance teams keep the series for breakdown work, because the O-ring boss end is common on pumps, motors and valve blocks while the supply connections are BSPP.

High-pressure test benches. Test circuits often mix BSPP manifolds with SAE O-ring boss gauge and instrument ports, and a rigid straight body with two face seals holds position on a panel.

OEM assembly lines. For a new build the series can be supplied to a drawing with a fixed plating, O-ring compound and bonded seal choice, so the line receives one part number per junction instead of a bushing plus a separate adapter.

6. Replacement and Cross-Reference Guide

Cross-reference this series by standard, thread and sealing method only, never by another maker’s catalogue number. Identify the two port standards on the part being replaced, then match the sizes and the O-ring code.

Measure these three things. First, the thread: on the BSPP side measure the outside diameter and count the threads per inch and match the G column, such as G1/2″X14. On the SAE side measure the outside diameter of the straight thread and count the threads per inch, for example 7/8″X14 or 1.1/16″X12, and confirm it is a straight thread and not a taper. Second, the seal: at the SAE end check for the undercut at the base of the thread where the O-ring sits, and measure the O-ring inside diameter and cross section. Third, the seat: at the BSPP end look inside the port. A 60° cone means the stud seals on the cone; a flat face means it seals on a bonded washer.

Replacement rules. A part with a straight UNF O-ring boss end is replaced by the same nominal size and O-ring code from this series. If the port is a 37° flare or a 74° inverted flare instead, it is not an O-ring boss port and this series is not the equivalent. If the BSPP port carries a BSPT taper thread, this series is also not the equivalent, because the BSPP end here is a parallel G thread.

7. Ordering, Packaging and Delivery

To order, give the series code plus the full part number, both thread sizes, the O-ring code, the seal material, the plating and the quantity, for example: 1BO series, 1BO-08-12, G1/2″X14 to 1.1/16″X12 with O912, FKM O-ring and FKM bonded seal, trivalent chromium zinc plating on carbon steel, 500 pieces. If the BSPP port is a 60° cone port, say so and the bonded washer is dropped from the quote.

Packaging. Parts are packed in cartons with the part number and quantity labelled, in bulk or in poly bags as the order requires, and can be labelled for distributor shelves or for direct-to-line OEM delivery. O-rings can be supplied pre-fitted or in a separate bag per the order, and mixed-size cartons are labelled line by line.

Samples and lead time. Sample quantities are available for validation before a production order, including with the nominated O-ring compound and plating, and lead time is confirmable per order and per size once the specification is fixed.

8. FAQ

What is the difference between BSPP and BSPT, and can they be interchanged? BSPP (G thread, ISO 228-1) is a parallel thread where pressure tightness is not made on the threads, so the joint seals on a 60° cone seat or on a bonded washer against a flat face. BSPT (R, Rc, Rp thread, ISO 7-1) is a taper thread where pressure tightness is made on the threads and a sealant is required. They are not interchangeable: forcing a taper male into a parallel female port damages both threads and will not seal reliably.

What is the difference between a 60° cone seat and a bonded seal, and which should I choose? The 60° cone seat seals metal to metal where the male cone meets the matching cone in the port and needs no extra sealing element. A bonded seal (Dowty-type washer) seals on a flat face and is compressed between the hex shoulder and the port face. Choose by the BSPP port you have: a cone calls for the cone seat, a flat face calls for the bonded washer. The SAE O-ring boss end is separate and always seals with its O-ring on the boss face.

How do I identify the correct 1BO size? Read the two ports, not the old part alone. Measure the BSPP thread and match it to the G column, then measure the straight UNF thread at the O-ring boss port and match it to the F column, and pick the row where the two meet. Then confirm the O-ring code in that row is the O-ring you intend to fit, since the code changes with the SAE size.

What seal material should I select for my fluid and temperature? NBR covers general hydraulic oil service at approximately -30°C to +100°C. FKM (Viton-type) suits higher temperatures and many aggressive fluids at approximately -20°C to +200°C. EPDM suits water-based fluids and steam at approximately -40°C to +120°C and is not compatible with mineral oil. At this series the O-ring material matters most, because at the SAE O-ring boss end it is the only sealing element.

How is the working pressure of this adapter determined? Pressure is not fixed across the series: it follows the size, the body wall thickness, the sealing method at each end and the material, and it is confirmed per order by HENGHUA engineering with the quotation. The condition of the boss face and the O-ring compound also influence the practical limit, so state the system working pressure on the inquiry and the rating can be reviewed against it.

What is the minimum order quantity and can I get samples? Sample quantities can be supplied for validation, including with a nominated O-ring compound and plating, so both face seals can be checked on your own ports before a production commitment. Minimum order quantity is confirmed per order because it depends on the size mix and the material. Send the part numbers with the annual quantity and both figures come back with the quotation.

Which O-ring belongs to each SAE O-ring boss size? The O-ring code is listed against every row of the chart, from O904 on the 7/16″X20 end to O924 on the 1.7/8″X12 end, and it is part of the part number family rather than a free choice. Use the code in the row you ordered, and confirm the O-ring compound with the fluid on the inquiry.

Is the L series the same as a heavy-duty O-ring boss port? No. This series uses the light-duty L series stud end to ISO 11926-3, which is the standard behind the chart sizes on this page. If your port drawing calls for a different duty series or a different size family, send the port drawing and HENGHUA confirms whether a standard or drawing-based part applies.

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