316L stainless steel turnbuckles for marine rigging, cable railing, architectural tensioning, and offshore structures. Open body, closed body, and toggle types. Eye, Jaw, Hook, and Toggle end fittings. M6–M36. WLL die-stamped on every unit.
A turnbuckle is a mechanical tensioning device with two threaded studs, one left-hand and one right-hand, turning inside a central body. Rotating the body draws both studs inward or pushes them outward, applying or releasing tension on the connected rod, cable, or wire rope without twisting the load. Stainless steel resists the corrosion that would otherwise seize a carbon-steel unit's threads in marine or outdoor service.
Body style drives inspection access, thread protection, and aesthetics. End fittings are independent, so any combination (Eye, Jaw, Hook, Toggle) can be specified with any body type.
The open frame exposes both threaded studs, allowing visual inspection of remaining thread engagement, a mandatory safety check before tightening. Thread engagement markers machined on the studs confirm minimum engagement (six turns) is maintained. The most widely used body style for marine rigging, structural tension rods, and agricultural fencing where periodic adjustment and easy inspection are required.
A solid cylindrical barrel that fully encloses the threaded studs, protecting the thread form from salt water and contamination between adjustment events. The hex flats machined on the barrel accept a spanner for adjustment. Preferred for yacht standing rigging and architectural cable railing where both corrosion protection and clean visual profile are required.
Toggle (flat-blade) end fittings pivot on a pin, allowing the turnbuckle to articulate in the plane of the bolt axis. This eliminates the bending moment that deforms rigid eye and jaw fittings when the tension rod and its anchor point are not perfectly co-axial. Toggle configuration is specified for architectural glass facades, roof canopy tension rods, and bridge handrails.
End fitting mismatch, like a side-loaded jaw or an eye too small for the connecting shackle pin, is the most common installation error in rigging assemblies. Specify the connection geometry at both anchor points before ordering.
Both ends connect via pin through the eye. The most versatile combination, since it works at any angle when correctly sized to the connecting pin diameter.
Fork ends on both sides. Direct pin connection to brackets. Cotter pin security. Best for removable connections to fixed anchors.
Most common marine/rigging combination. Eye to shackle, jaw directly to chainplate or bracket. Handles mixed anchor geometry.
Hook for quick installation without tools. Not for overhead lifting or safety-critical applications. Light duty and non-permanent.
Toggle articulates in-plane. Specified for structural/architectural work when connection geometry cannot guarantee perfect axial alignment.
Both ends articulate. For glass facades and canopies where both anchor points may shift with thermal expansion or structural movement.
WLL values below apply to 316L bodies under static axial tensile load at ambient temperature. Rated to a 5:1 design factor, consistent with ASME B30.26 practice for adjustable rigging hardware. Always verify suitability for your specific loading, environment, and governing standard before installation.
| Thread | Take-Up | WLL (kN) | WLL (lbs) |
|---|---|---|---|
| M6 | 50 mm | 1.2 kN | 270 lbs |
| M8 | 70 mm | 2.2 kN | 490 lbs |
| M10 | 90 mm | 3.6 kN | 810 lbs |
| M12 | 110 mm | 5.2 kN | 1,170 lbs |
| M14 | 130 mm | 7.0 kN | 1,570 lbs |
| M16 | 150 mm | 9.6 kN | 2,160 lbs |
| M20 | 180 mm | 15.0 kN | 3,370 lbs |
| M24 | 220 mm | 21.6 kN | 4,860 lbs |
| M30 | 270 mm | 33.6 kN | 7,560 lbs |
| M36 | 320 mm | 49.0 kN | 11,020 lbs |
Galvanized and stainless turnbuckles can look identical in a catalogue photo. In marine or coastal service, the zinc coating that protects galvanized steel is the difference between years of service and one failed season.
The lowest-cost option, and adequate for indoor or freshwater rigging where the zinc coating only has to shield against ordinary weather. The zinc layer sacrifices itself to protect the steel underneath, but it corrodes progressively. In saltwater or continuous salt spray, the coating fails and the base steel rusts, typically within one to two seasons of coastal exposure. Profab does not manufacture galvanized turnbuckles; noted here for comparison.
Budget Freshwater OnlyAppropriate for indoor tensioning assemblies in genuinely non-chloride environments: dry warehouse bracing, inland agricultural buildings, controlled-venue theatrical rigging. More cost-effective than 316L with excellent machinability. Do not specify within 10 km of a coastline or for any assembly subject to salt spray or humid coastal air.
Indoor Dry Ag TheatreThe minimum acceptable grade for turnbuckles in any coastal, marine, or chloride-rich environment. The 2–3% molybdenum addition raises the PREN to ≥ 24, the corrosion resistance threshold at fine-pitch thread roots where seawater and chloride concentrate. Profab sources certified 316L raw stock and machines every turnbuckle body and stud to your specified thread and body length.
Marine Offshore OutdoorNeed more strength at less weight for deepwater or racing use? Duplex 2205 (PREN 34–36) is available custom-sourced, M10–M36 on request.
Each body starts as solid round 316L bar, saw-cut to length. CNC turning shapes the outside diameter and bores the internal left-hand and right-hand threads that let one body draw both studs inward on the same rotation. CNC milling then cuts the hex flats on a closed body, or the open slots and inspection holes on an open body. Machining from solid bar, rather than forging or casting, holds tighter dimensional control on thread pitch and take-up length across a production run.
A turnbuckle is required wherever an assembly needs in-line tension adjustment without rotating the connected load, and where the service environment makes corrosion resistance non-negotiable.
Closed-body 316L turnbuckles at the lower chainplate connections of shrouds, forestays, backstays, and inner forestays. Duplex 2205 for offshore passage and racing specifications where weight and extreme corrosion resistance are simultaneously required.
Closed-body 316L turnbuckles tension the horizontal wire rope runs of balustrade systems on decks, balconies, and staircases. Toggle end fittings are specified where post-drilling geometry doesn't guarantee perfect axial alignment.
Toggle/Toggle 316L turnbuckles for the tension rod systems supporting glass canopy panels and point-fixed glazing facades. Both ends must articulate to absorb thermal expansion and structural movement.
Open-body 316L or Duplex 2205 for platform structural cross-bracing, mooring pre-tensioning, and cargo securing on commercial vessels. Classification societies may require specific material documentation, so confirm your project's requirements at enquiry.
Open-body 316L for wire fence tensioning and aquaculture cage mooring at coastal farms, environments where galvanised hardware fails within one to two seasons. 304 acceptable for inland, non-coastal applications with no direct salt exposure.
Open-body turnbuckles for flying systems and truss tensioning, required by theatrical rigging codes so the rigger can visually confirm six turns of thread engagement before load is applied. Inspection holes on Profab open-body turnbuckles allow this check without measurement tools.
Every turnbuckle body and stud is machined from certified 316L stock, so the molybdenum content that raises corrosion resistance at the thread roots doesn't vary batch to batch. The grade you specify is the grade you receive.
Standard take-up ranges don't fit every long-span cable railing or roof tension rod. Profab machines extended-take-up bodies to your specified length rather than limiting you to catalogue increments.
Eye, Jaw, Hook, and Toggle end fittings are machined independently from the body. Specify any combination, such as Eye/Jaw, Toggle/Toggle, or Hook/Eye, on Open, Closed, or standard body styles without a fixed catalogue pairing.
Not seeing your question? Email us at [email protected] and we typically reply same day.
Open body: where periodic visual thread engagement inspection is required or specified by rigging codes (theatrical, commercial marine, offshore). The exposed frame allows the rigger to confirm minimum engagement without tools. Closed body: where the threads need protection from salt water and contamination between adjustment events, such as yacht standing rigging and architectural cable railings. Also preferable aesthetically for high-visibility installations. WLL, material, and end fitting combinations are identical between the two; the choice is driven by inspection requirement, environmental protection, and visual preference.
Standard turnbuckles are not certified or rated for overhead lifting duty. Overhead lifting hardware must comply with ASME B30.26 or EN 13411, be individually proof-load tested, and carry a documented certificate. Standard turnbuckles are rated for static tensile loads in rigging and structural assemblies, not the dynamic shock loads of crane and hoist operations. If you require a tensioning device for an overhead lifting application, specify a rigging screw that carries an explicit overhead lifting certification with individual test documentation.
Stainless steel galls: the asperities on two stainless thread surfaces cold-weld under frictional contact during assembly. Once galling starts, it progresses rapidly and the threads can seize completely. This is not a material defect; it is the physical property of austenitic stainless under dry sliding contact. Prevention is straightforward: apply nickel-based or PTFE anti-seize compound to both thread forms before assembly, and use only a spanner or turnbuckle wrench, never a power tool. Profab applies a light coating of anti-seize to all turnbuckle threads before protective packaging. For more on why this happens on stainless threads generally, see Why Do Jam Nuts Gall on Stainless Steel Rod Ends?
Yes. Send the original turnbuckle as a physical sample, or provide its thread size, take-up length, body style, and end fitting type, and Profab machines a matching replacement. This is common on yacht standing rigging and architectural cable railing installations where the original OEM turnbuckle brand has discontinued the exact part or size.
Provide your required parameters, including body type, end fitting combination, thread size, stainless steel grade, and quantity.
We will work on the best solution based on your request and send you a specific quote within 24 hours.
30 days standard. Samples before full production run on new custom parts. QC report before shipment.
Sea, air, or express courier. Material certs and inspection report inside every box.
Installing with wire rope? Jam nuts, thimbles, and safety wire are commonly ordered alongside turnbuckles, so mention your requirements when you request a quote.
If you already have the drawings, please send email to [email protected] directly for an instant quote.
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