Tesco Steel & Engineering manufactures SAE J518 split flanges — the 4-bolt, two-half clamp configuration used to connect hydraulic pumps, motors, valves, and cylinders to pipe and hose ends. Available in Code 61 (3000 PSI) and Code 62 (6000 PSI) series. SS 316, Duplex, Carbon Steel, Inconel, Monel. Size 3/8" to 5" NB. 34–420 bar. ISO 9001:2015 certified. Made in India.
TES-LOK SAE Split Flange
Flat Face Split Flange
SAE Flange Range
Split flanges are governed by the same SAE J518 / ISO 6162 standard as mono (single-piece) SAE flanges, and come in the same two pressure series: Code 61 (standard pressure, 3000–5000 PSI) and Code 62 (high pressure, 6000 PSI). The split clamp halves are the most common SAE flange form in mobile and industrial hydraulics because they greatly simplify assembly and servicing.
| Feature | Split Flange (Two-Half Clamp) | Mono Flange (Single-Piece) |
|---|---|---|
| Construction | Two semi-circular clamp halves, 2 bolts each | One-piece solid flange ring, 4 bolts |
| Installation | Halves wrap around a captive flange head / weld collar; pipe need not rotate | Flange slides over pipe end before pipe is welded/connected; pipe must be free |
| Serviceability | Excellent — remove halves to disconnect pipe without disturbing the rest of the line | Lower — requires disconnecting/rotating the pipe assembly |
| Tight-space assembly | Easier — each half handled separately in confined spaces | Harder — full ring must pass over the pipe end |
| Part count | 2 clamp halves + 4 bolts per connection | 1 flange + 4 bolts per connection |
| Best for | Field-serviceable hydraulic lines; retrofit; tight spaces | Permanent factory-assembled connections |
| Criterion | Code 61 (Standard Pressure) | Code 62 (High Pressure) |
|---|---|---|
| SAE / ISO standard | SAE J518 Code 61 / ISO 6162-1 | SAE J518 Code 62 / ISO 6162-2 |
| Pressure rating | 3000–5000 PSI (207–345 bar) — size dependent | 6000 PSI (420 bar) — all sizes |
| Flange head diameter | Larger head for same port size | Smaller, thicker head |
| Bolt size | Smaller bolts | Larger bolts, closer spacing |
| Interchangeable? | No — different bolt pattern from Code 62 | No — verify port code before ordering |
| Typical use | Pump suction/return, medium-pressure mobile hydraulics | Pump outlet, press circuits, heavy industrial hydraulics |
| Connection Type | Description | Best Application |
|---|---|---|
| Threaded NPT | Flange head with female NPT thread on the back for threaded pipe | Threaded hydraulic pipe systems |
| Threaded BSPP | Female BSPP (G) parallel thread with O-ring / bonded seal | European hydraulic systems |
| Socket Weld (Weld-In) | Counter-bore socket — pipe slips in, fillet welded; clamp halves wrap the head | Welded hydraulic pipe systems |
| Butt Weld (Weld-On) | Plain / bevelled weld end butt-welded to pipe | High-integrity large-bore welded hydraulic lines |
| Flat Face Split | Flat-faced split flange head for flat-face mating ports | Connections where flat-face sealing is specified |
| Parameter | Details |
|---|---|
| Brand | TES-LOK (Tesco Steel & Engineering) |
| Size Range | 3/8" to 5" NB |
| Pressure Series | Code 61 — 3000 PSI | Code 62 — 6000 PSI |
| Working Pressure | 34 bar to 420 bar (depending on size and code) |
| Configuration | Two-half split clamp (2 bolts per half, 4 bolts per connection) |
| Connection Types | Threaded NPT, Threaded BSPP, Socket Weld (Weld-In), Butt Weld (Weld-On), Flat Face Split |
| Standards | SAE J518 | ISO 6162-1 (Code 61) | ISO 6162-2 (Code 62) |
| O-Ring Material | NBR (standard), Viton (FKM), EPDM — by hydraulic fluid type |
| Certifications | ISO 9001:2015 | EN 10204 3.1 MTC | PMI (XRF) on request | Hydrostatic test cert |
| Material Family | Grades / ASTM Spec |
|---|---|
| Stainless Steel Split Flanges | ASTM A182 F304 / 304H / 304L / 316 / 316H / 316L / 316Ti, 309, 310, 317L, 321, 347, 904L |
| Duplex & Super Duplex Split Flanges | ASTM A182 F51 (2205), F53 (2507), F55 (Zeron 100) |
| Alloy Steel Split Flanges | ASTM A182 F5, F9, F11, F21, F22, F91 |
| Carbon Steel Split Flanges | ASTM A105 (standard hydraulic flange material) |
| Low-Temp Carbon Steel (LTCS) | ASTM A350 LF2 — cryogenic / low-temperature service |
| Copper-Nickel Split Flanges | C70600 (90/10), C71500 (70/30), C71640 |
| Nickel Split Flanges | UNS N02200, UNS N02201 |
| Monel Split Flanges | UNS N04400, UNS N05500, Alloy 20 |
| Inconel Split Flanges | UNS N06600, N06601, N06625, N08800, N08810, N08825 |
| Hastelloy Split Flanges | UNS N10276, N06022, N10665, N06455 |
| Titanium Split Flanges | Gr. 1, Gr. 2, Gr. 3, DTH 3.7035, DTH 3.7055 |
Download the full TES-LOK split flange dimension tables for the 3000 PSI (Code 61) and 6000 PSI (Code 62) series — clamp half dimensions, bolt circle, flange head diameter, bolt size, and bore for each NB size:
📄 3000 PSI Split Flange Dimensions (PDF) 📄 6000 PSI Split Flange Dimensions (PDF) 📄 Flat Face Split Flange Dimensions (PDF)| O-Ring Material | Temperature Range | Compatible Hydraulic Fluid | Avoid With |
|---|---|---|---|
| NBR (Nitrile) — Standard | −40°C to +100°C | Mineral oil hydraulic fluids (ISO HM / HV), diesel | Phosphate ester, Skydrol, hot water |
| Viton (FKM) | −20°C to +200°C | High-temperature mineral oils, fire-resistant HFD fluids | Skydrol (phosphate ester), hot water/steam |
| EPDM | −40°C to +150°C | Phosphate ester (Skydrol) fluids, water-glycol (HFC) | Mineral oils, petroleum-based fluids |
Clamp half dimensions, bolt circle, bolt hole size, and O-ring groove are machined to SAE J518 / ISO 6162 tolerances for Code 61 and Code 62 — ensuring direct interchangeability with hydraulic pumps, motors, and valves from any OEM worldwide.
The split clamp halves can be removed and refitted without disturbing the pipe or hose run — ideal for maintenance, retrofit, and tight-space installations where a one-piece flange cannot be passed over the line. Reduces downtime during hydraulic component replacement.
From standard Carbon Steel A105 to SS 316, Duplex, Inconel, Monel, and Hastelloy for corrosive and marine hydraulic systems. Single-source supply across the full alloy spectrum with EN 10204 3.1 MTC and PMI on request.
Code 62 (6000 PSI / 420 bar) split flanges for high-pressure hydraulic press circuits, heavy machinery, and mobile equipment outlet ports — where threaded connections cannot reliably hold pressure and vibration resistance is essential.
Full dimensional data for 3000 PSI and 6000 PSI split flange series available as downloadable PDF charts — clamp half dimensions, bolt circle, flange OD, bolt size, and bore for every NB size.
Split flanges are manufactured on the same CNC machining centres and to the same QA/QC discipline that govern our full range of ASME, DIN, and EN flanges. ISO 9001:2015 certified, with material traceability and hydrostatic testing on every batch.
| Industry | Typical Use Point | Why Split Flange Preferred |
|---|---|---|
| Mobile & Construction Equipment | Excavator, loader, crane hydraulic pump and motor port connections | Two-half clamp allows hose/pipe replacement in the field without removing the whole line |
| Industrial Hydraulics | Power unit pump outlet, manifold block ports, press circuits | Code 62 handles 6000 PSI; split design eases servicing in packed power packs |
| Marine & Offshore | Deck machinery, winch, crane and steering gear hydraulics | SS 316 / Duplex split flange resists marine corrosion; serviceable on deck without dismantling |
| Oil & Gas | BOP control hydraulics, drilling rig and top-drive hydraulic circuits | High-pressure Code 62 with corrosion-resistant alloys for offshore environment |
| Steel & Metals | Rolling mill and continuous casting hydraulic systems | Heavy-duty split clamp withstands cyclic loading; quick to service during shutdowns |
| Mining | Haul truck, shovel, and drill rig hydraulics | Split flange survives extreme shock/vibration and speeds field repairs |
| Agriculture & Forestry | Tractor, harvester, and forestry machine hydraulic circuits | Field-serviceable connection for equipment maintained away from workshops |
| Wind Energy | Turbine pitch, yaw, and brake hydraulic systems | Split clamp eases servicing in confined nacelle spaces under constant motion |
Q1. What is the difference between a split flange and a mono (single-piece) SAE flange?
A split flange uses two semi-circular clamp halves (two bolts each) that wrap around a captive flange head or weld collar. A mono flange is a single solid flange ring with four bolt holes. Functionally they make the same SAE J518 connection and use the same O-ring seal, but the split design allows the pipe/hose to be connected and disconnected without rotating or fully removing the line — which is why split flanges dominate field-serviceable hydraulic installations. Mono flanges suit permanent factory-assembled connections.
Q2. How many bolts does an SAE split flange use?
A standard SAE split flange uses four bolts per connection — two bolts through each of the two clamp halves. The four bolts are tightened in a diagonal cross pattern to clamp both halves evenly onto the flange head and compress the O-ring against the port face. Some very small sizes use a 2-bolt single-piece flange, but the 4-bolt two-half split is the standard SAE J518 configuration.
Q3. What is the difference between SAE Code 61 and Code 62 split flanges?
Code 61 is the standard-pressure series (3000–5000 PSI / 207–345 bar) and Code 62 is the high-pressure series (6000 PSI / 420 bar). For the same nominal port size, Code 62 has a smaller, thicker flange head, larger bolts, and closer bolt-hole spacing to handle higher pressure. They are not interchangeable — a Code 61 split flange will not fit a Code 62 port and vice versa. Always confirm the code stamped on the equipment port before ordering.
Q4. Why are split flanges preferred over threaded connections in hydraulics?
Split flanges handle far higher pressure than threaded fittings, do not loosen under the vibration and pressure pulsation common in hydraulic systems, and can be connected/disconnected without rotating the pipe or hose. The O-ring face seal is more reliable than thread sealing, and the two-half clamp distributes load evenly while allowing field service. Above about 1" NB and 3000 PSI, SAE split flanges are the standard hydraulic connection method worldwide.
Q5. What O-ring material should I use for Skydrol (phosphate ester) hydraulic fluid?
Use EPDM. Skydrol and other phosphate ester fire-resistant hydraulic fluids attack NBR (nitrile) and Viton (FKM) O-rings, causing rapid swelling and seal failure. EPDM is compatible with phosphate ester fluids. Conversely, EPDM must NOT be used with mineral-oil hydraulic fluids — for those use NBR (standard) or Viton (high temperature). Always match the O-ring elastomer to the specific hydraulic fluid.
Q6. Can split flanges be supplied in stainless steel or duplex for marine hydraulics?
Yes. Split flanges are available in SS 304, SS 316 / 316L, Duplex 2205, and Super Duplex 2507 for marine, offshore, and corrosive-environment hydraulic systems, with EN 10204 3.1 material test certificates and PMI on request. SS 316 and Duplex resist the chloride-induced corrosion that attacks standard Carbon Steel split flanges in marine atmospheres.
Q7. Can I replace a mono flange with a split flange on the same port?
Yes, provided the code (61 or 62) and nominal size match the port. The port-side dimensions (bolt circle, flange head seat, O-ring groove) are identical between split and mono flanges of the same SAE code and size — they are simply different ways of clamping to the same standardised port. Switching to a split flange is a common upgrade to make an existing hydraulic connection field-serviceable.
Q8. Do you provide split flange dimension charts?
Yes. Full dimension charts for the 3000 PSI (Code 61) and 6000 PSI (Code 62) split flange series, plus flat-face split flange dimensions, are available as downloadable PDF documents on this page. These give clamp half dimensions, bolt circle, flange head OD, bolt size, bolt-hole spacing, and bore for every NB size. For any size or configuration not in the standard charts, contact our technical team.