Threaded Rods (All Thread Rod / Stud Rod)
In HVAC suspension, strut-channel supports, and embedded anchoring, failures rarely start with the rod “snapping”. They start with small, repeatable issues: thread galling during tightening, preload loss after thermal cycling, zinc coatings cracking at cut ends, or a coupling nut backing off under vibration. Our threaded rods (also called all thread, threaded bar, fully threaded rod, or continuous thread rod) are built around standardised threads, controlled mechanical properties, and traceable material certs—so your installation torque translates into predictable preload, and your maintenance team stops chasing recurring loosening and corrosion-driven rework.
- Match DIN/ISO/ASTM standards
- Control pitch and thread class
- Offer HDG for outdoor corrosion
- Prevent galling with proper finishes
- Provide mill/3.1 traceability
- Cut-to-length, deburred ends
Technical Specifications
Product Name
Threaded Rods / All Thread Rods
Standards
DIN 976-1 (metric threaded rod, replaces DIN 975)
Material
Carbon steel (e.g., C35/C45), alloy steel (e.g., 42CrMo4), stainless steel (A2/304, A4/316)
Grades
ISO 898-1 classes (e.g., 4.8 / 5.8 / 8.8 / 10.9*), stainless per ISO 3506 (A2-70 / A4-70 / A4-80), ASTM A193 B7 (inch)**
Diameter Range
Metric: M6–M36 (typical); Inch: 1/4″–1-1/2″ (typical)
Surface Finish
Plain, Zinc plated, Yellow zinc, Black oxide, Hot-dip galvanised (HDG)
Certifications
ISO 9001; EN 10204 3.1 on request; RoHS/REACH on request; IATF 16949 capability on request
“Torque goes up, preload doesn’t.”
What happens: Stainless all thread in 304/316 can gall (adhesive wear) during tightening, especially in dry assembly. Torque spikes, threads seize, and the joint never reaches target preload.
How we solve it: Specify ISO 3506 grades (A2-70 / A4-80) with controlled surface condition; recommend anti-seize for stainless, and verify pairing with nut material/finish to reduce galling risk.
Corrosion starts at cut ends.
What happens: In field cut-to-length installations, zinc coatings are removed at the cut; corrosion initiates at exposed steel, then undermines the joint and increases maintenance.
How we solve it: Offer hot-dip galvanised threaded rod for outdoor/structural environments; provide factory-cut, chamfered ends to protect coating integrity and reduce cross-threading.
Vibration loosening in suspended systems.
What happens: In HVAC hangers and machine frames, micro-movement causes preload decay and nut rotation—especially when mating surfaces embed or paint creeps.
How we solve it: Recommend pairing with prevailing torque lock nuts (all-metal lock nuts) or a jam-nut arrangement; for structural anchoring, specify adequate thread engagement and hardened washers where bearing stress is high.
Coating + strength mismatch.
What happens: High-strength alloy rods (e.g., Class 10.9 or ASTM B7) combined with uncontrolled electroplating can increase hydrogen embrittlement risk.
How we solve it: For high-strength requirements, align finish selection with the grade (e.g., controlled plating/baking, or alternative finishes), and supply traceable heat/lot documentation.
Threaded rods have no head, so bolt dimensions like k (head height) are not applicable. For procurement and drawing checks, the decisive dimensions are thread diameter (d), pitch (P), mating nut wrench size (s), and typical coupling nut length l.
Example Metric Coarse Thread Sizes (common industrial selection):
| Thread Size (d) | Pitch P (ISO metric coarse) | Nut Across Flats s (ISO 4032) | Coupling Nut Length l (DIN 6334, typical) | Thread Tolerance (common) |
|---|---|---|---|---|
| M6 | 1.0 | 10 | 18 | 6g |
| M8 | 1.25 | 13 | 24 | 6g |
| M10 | 1.5 | 17 | 30 | 6g |
| M12 | 1.75 | 19 | 36 | 6g |
| M16 | 2.0 | 24 | 48 | 6g |
| M20 | 2.5 | 30 | 60 | 6g |
Notes for purchasing specs:
If your BOM calls out fine pitch, state it explicitly (e.g., M12×1.25) and confirm nut availability.
For inch products, specify thread series (UNC/UNF) and class (e.g., 2A for external threads).
convert tightening torque into controlled preload, while preventing thread damage, galling, and loosening.
Define the joint requirement (Preload vs. positioning)
Hanger rods often need positioning rather than maximum preload; over-torque can crush channels, strip nuts, or bend rods.
Structural clamping joints should target a defined preload (engineering calculation per your design method, commonly aligned with VDI-style bolted joint practice).
Torque–Preload control (Torque, Preload, Lubrication)
Torque is highly sensitive to friction. Typical friction factor ranges:
Dry steel-on-steel: higher and less consistent
Lubricated: lower and more consistent
For stainless threaded rods, use anti-seize to reduce galling and torque scatter.
If preload is critical, consider validated methods (e.g., torque–tension testing per ISO 16047) rather than generic torque charts.
Washer selection (Washers)
Use flat washers (ISO 7089 / DIN 125) to reduce bearing stress and protect coatings/painted surfaces.
For slotted channels or soft materials, increase washer OD or use structural plates to avoid embedment-related preload loss.
Hole clearance (ISO 273)
When rods pass through plates, use clearance holes per ISO 273 to avoid side-loading that introduces bending and fatigue risk.
If alignment is poor, fix the bracket geometry—do not “force” the rod through undersized holes.
Thread engagement and coupling (Critical for safety)
In coupling nuts (DIN 6334), ensure adequate engagement on both sides; incomplete engagement is a common field failure mode.
Where vibration is present, use a lock nut or jam nut strategy to prevent rotation.
Cutting and field modification
After cutting: chamfer/deburr the end, chase threads if needed, and re-protect exposed steel (especially for zinc plated parts).
Avoid welding on high-strength alloy rods unless the material is specified as weldable and the coating is removed; welding can change heat treatment and coating behaviour.
Related Products
FAQ
What is a threaded rod (all thread rod) used for?
A threaded rod is a continuous or partially threaded fastener used for anchoring, suspension, and adjustable assemblies where length and positioning matter more than a bolt head. It’s common in HVAC hangers, strut channel systems, concrete anchoring, and equipment framing.
What standard should I specify for metric threaded rods—DIN 975 or DIN 976?
For current metric purchasing, specify DIN 976-1 (DIN 975 is largely superseded). DIN 976-1 defines the threaded rod form and helps ensure interchangeability for nuts and coupling nuts.
How do I choose the right grade for threaded rods?
Choose grade based on required preload, service temperature, and corrosion environment. Typical options include ISO 898-1 classes (e.g., 4.8/8.8) for carbon/alloy steel, ISO 3506 (A2-70/A4-80) for stainless, and ASTM A193 B7 for high-strength inch applications.
Why do stainless steel threaded rods seize during tightening?
Stainless rods can seize due to galling—adhesive wear between similar stainless threads under load. Use anti-seize lubrication, avoid dry assembly, and match nut material/finish appropriately to reduce seizure risk.
How much torque should I apply to a threaded rod assembly?
Torque should be set to achieve the required preload based on friction conditions, not guessed from rod size alone. If preload is critical, validate torque–tension behaviour (e.g., testing aligned with ISO 16047) and control lubrication, washers, and surface condition to reduce scatter.