Titanium Screws for Marine Environment \| Gr2/R50400 & Gr5/R56400, ASTM F468, Seawater/Crevice/Galvanic Isolation, EN 10204 3.1, Baoji

Product Overview

Reviewed and maintained by the Engineering Team, Shaanxi Qianyi Tuoda Technology Co., Ltd.

Titanium Screws for Marine Environment | Gr2 vs Gr5, ASTM F468, Galvanic Isolation + Anti-Galling, MTC 3.1

Meta Description: Titanium screws for marine environment — Gr2 (R50400) corrosion-first seawater duty, Gr5 (Ti-6Al-4V/R56400) high-preload joints. ASTM F468/F468M, DIN912/ISO7380, rolled thread, 100% PMI + GO/NO-GO gauged, EN 10204 3.1. Galvanic isolation + anti-seize guidance included.

Why Titanium, Why Not 316 in Seawater

Titanium builds a self-healing TiO₂ passive film in flowing or stagnant seawater. Scratch it, oxygen rebuilds it. That is why titanium screws survive splash zone, submerged clamps, desalination skids and offshore topside where 316 pits under deposit/chlorine excursion. Density ~4.5 g/cm³ — about 40-45% lighter than steel, same corrosion class for most marine duty.

Gr2 or Gr5 — The Only Question That Matters

Rule of thumb: corrosion-dominated → Gr2; strength/weight-dominated → Gr5. "Stronger" is not automatically "better in seawater".

Screw Forms We Supply

• Socket head cap (DIN912 / ISO4762)
• Button head (ISO7380), flat/countersunk (DIN965), pan head
• Hex head cap screw (DIN933 paired form)
• Set screw, shoulder screw, custom drive (Torx/12-point) on drawing
• Size range M3-M36 metric; #6-3/8" UNC/UNF on request

Standards & Route

• Finished screw: ASTM F468 / F468M (bolts, screws, studs)
• Bar feed: ASTM B348 Gr2/Gr5
• Thread: ISO 6g / UNC-2A / UNF-2A; rolled preferred
• Nut mate: F467 (same grade); Gr5 screw + Gr5 nut for high preload

Three Marine Failure Modes (and how the page defeats them)

1. Galling / cold-seize

• Never assemble dry — clean threads + MoS₂ / PTFE / dry-film anti-seize
• Rolled thread keeps grain flow at root → less friction, better fatigue
• Torque from validated preload table, not steel values; re-check 24h after PTFE

2. Galvanic attack on the OTHER metal

• Titanium is noble in seawater — it will not corrode, but accelerates CS/Al/Zn contact
• Isolate: PTFE sleeve, neoprene bushing, dielectric washer, sealed joint
• Design-side decision, not installer's — state isolation in drawing/PO

3. Crevice + hot brine

• Gr2 handles most seawater crevices
• Hot chloride (>80°C) / reducing acid excursion → Gr7 (Pd) or Gr12 evaluated, not auto-Gr5

QC Before Pack (marine-grade release)

1. 100% PMI/XRF — Gr2 vs Gr5 are dimensionally identical, grade mix is a failure mode, not a typo
2. Heat No. bar → bag tag (parent = finished)
3. GO/NO-GO thread gauge per piece
4. Passivation/clean, ferroxyl iron-check on request
5. EN 10204 3.1: chemistry + tensile from bar heat, QA-signed
6. 3.2 (DNV/BV/SGS/LR) PO-fronted, cannot back-build from 3.1

Where They Go

• Desalination skids, seawater pump covers, exchanger bonnet screws
• Offshore topside clamps, ROV housings, cable tray
• Yacht/deck hardware, hatch hinges, anodic-managed rigging
• NEV/chassis marine-adjacent, aquarium life-support frames

RFQ Template (copy-paste)

Screw type: socket cap / button / flat / hex / custom ___
Size: M___ × length ___mm (or UNC/UNF __"-__TPI)
Thread: metric coarse/fine / UNC / UNF ___
Grade: Gr2(R50400) / Gr5(R56400) / Gr7 / Gr12 ___
Drive: Allen / Torx T__ / 12-point ___
Surface: pickled / polished / anodize colour(code) ___
Isolation required: PTFE sleeve / neoprene washer / none ___
Anti-gall lube: MoS2 / PTFE / none ___
Mate nut grade: same / specify ___
Qty: ___
Cert: 3.1 / 3.2 (TPI ___)
Incoterm: EXW Baoji / FOB Shanghai / DAP ___

FAQ — Titanium Screws for Marine Use

Q1: Is Gr5 always better for boats?
A: No. Gr2 is the corrosion-first default for seawater; Gr5 only when preload/weight justifies the cost and hot-crevice SCC is ruled out.

Q2: Will titanium screws rust in saltwater?
A: Titanium itself stays passive in seawater; the risk is galvanic attack on the joined steel/aluminium, so isolate the joint.

Q3: Dry assembly OK?
A: Never for Ti-on-Ti or Ti-on-steel under load — galling/seize. Clean threads + approved anti-seize mandatory.

Q4: Can I replace 316 screws 1:1?
A: Dimensionally yes; mechanically re-check preload/torque (lower E-modulus) and add dielectric isolation.

Q5: Hot seawater + crevice >80°C?
A: Evaluate Gr7/Gr12, not Gr5. Medium + temperature decide grade, not "stronger".

Q6: PMI on every piece?
A: Yes for marine/structural — Gr2 and Gr5 look identical; cert alone is not enough without PMI.

Q7: Anodize for corrosion?
A: Colour anodize = ID coding only; hard anodize/dry-film for wear. Base corrosion resistance comes from the alloy + passive film.

Q8: 3.2 possible?
A: TPI at PO stage; witnesses test + gauge.

Q9: HF / dry chlorine / red fuming nitric?
A: Titanium excluded — red line, no workaround.

Q10: HS code?
A: WCO 6-digit 8108.90 base; fastener sub-heading via broker.

Request a Quote

Email: sales@[yourdomain].com

Send screw type + size + grade + isolation need + qty. Reply in 24h: heat status, EXW/FOB price, cert scope, dispatch window.

About: Baoji Titanium Valley marine screw line — Gr2 (R50400) corrosion-first, Gr5 (R56400/Ti-6Al-4V) strength-first, ASTM F468/F468M, DIN912/ISO7380, rolled thread, 100% PMI + GO/NO-GO gauged, EN 10204 3.1. Galvanic isolation and anti-seize guidance shipped with the pack — because a titanium screw fails on the joint, not the metal. No dry-assembly advice, no grade mix, no cert downgrade. Lot confirmed before PI; bag = MTC = heat.