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GB93 Lock Washer A4 Stainless

GB93 Helical Spring Lock Washer — A4 Marine Stainless Steel (SUS316), Whitened & Passivated

FULLERKREG GB93 helical spring lock washers are manufactured to GB 93-1987 standard in A4 marine-grade stainless steel (SUS316 / 06Cr17Ni12Mo2 / 1.4401) with a whitened and passivated surface finish. GB93 is one of the most widely used Chinese spring washer standards, and the A4 grade adds 2–3% molybdenum to the A2 (SUS304) composition, delivering significantly enhanced resistance to chloride corrosion, seawater, and aggressive chemical environments. A4 is the preferred choice for marine, offshore, coastal, chemical processing, and pool applications where A2 stainless is insufficient.

Product Highlights

  • Standard: GB 93-1987
  • Material: A4 Marine Stainless Steel (SUS316 / 06Cr17Ni12Mo2 / 1.4401)
  • Surface Treatment: Whitened & Passivated (bright silver, uniform stainless finish)
  • Size Range: M2 – M48
  • Function: Helical spring lock washer — anti-loosening via spring-back tension and bite-in effect
  • Key advantage over A2: Molybdenum addition (2–3%) — superior chloride, seawater & acid resistance
  • Hardness: ≥ 34 HRC or 336 HV (per GB 9/T94.1-2008)
  • Non-magnetic (austenitic), non-sparking
  • RoHS & REACH Compliant

Dimensional Specifications — GB93 Lock Washers (A4 Stainless, Whitened & Passivated)

All dimensions in millimeters (mm). Per GB 93-1987.

Size d min d max h nominal h min h max n min n max H min H max Weight (kg/1000pcs steel ref.)
M2 2.1 2.35 0.5 0.42 0.58 0.42 0.58 1.0 1.25 0.016
M2.5 2.6 2.85 0.65 0.57 0.73 0.57 0.73 1.3 1.63 0.033
M3 3.1 3.4 0.8 0.7 0.9 0.7 0.9 1.6 2.0 0.06
M4 4.1 4.4 1.1 1.0 1.2 1.0 1.2 2.2 2.75 0.15
M5 5.1 5.4 1.3 1.2 1.4 1.2 1.4 2.6 3.25 0.258
M6 6.1 6.68 1.6 1.5 1.7 1.5 1.7 3.2 4.0 0.47
M8 8.1 8.68 2.1 2.0 2.2 2.0 2.2 4.2 5.25 1.07
M10 10.2 10.9 2.6 2.45 2.75 2.45 2.75 5.2 6.5 2.06
M12 12.2 12.9 3.1 2.95 3.25 2.95 3.25 6.2 7.75 3.51
(M14) 14.2 14.9 3.6 3.4 3.8 3.4 3.8 7.2 9.0 5.51
M16 16.2 16.9 4.1 3.9 4.3 3.9 4.3 8.2 10.25 8.15
(M18) 18.2 19.04 4.5 4.3 4.7 4.3 4.7 9.0 11.25 10.98
M20 20.2 21.04 5.0 4.8 5.2 4.8 5.2 10.0 12.5 15.05
(M22) 22.5 23.34 5.5 5.3 5.7 5.3 5.7 11.0 13.75 20.24
M24 24.5 25.5 6.0 5.8 6.2 5.8 6.2 12.0 15.0 26.23
(M27) 27.5 28.5 6.8 6.5 7.1 6.5 7.1 13.6 17.0 37.88
M30 30.5 31.5 7.5 7.2 7.8 7.2 7.8 15.0 18.75 51.06
(M33) 33.5 34.7 8.5 8.2 8.8 8.2 8.8 17.0 21.25 72.43
M36 36.5 37.7 9.0 8.7 9.3 8.7 9.3 18.0 22.5 88.03
(M39) 39.5 40.7 10.0 9.7 10.3 9.7 10.3 20.0 25.0 118.2
M42 42.5 43.7 10.5 10.2 10.8 10.2 10.8 21.0 26.25 139.6
(M45) 45.5 46.7 11.0 10.7 11.3 10.7 11.3 22.0 27.5 163.4
M48 48.5 49.7 12.0 11.7 12.3 11.7 12.3 24.0 30.0 208.1

* Sizes in parentheses ( ) are non-preferred sizes. Weight reference values based on steel density ≈7.85 g/cm³. A4 stainless weights are approximately 2% higher (density 7.98 g/cm³). Please verify with your engineering team for critical applications.

Elastic Test Free Height — GB 9/T94.1-2008 Table 2

Minimum free height after elastic test (mm):

Size M3 M4 M5 M6 M8 M10 M12 M14 M16 M18 M20 M22 M24 M27 M30
Free height ≥ (mm) 0.9 1.0 1.25 1.6 2.1 2.4 2.8 3.2 3.8 3.8 4.4 4.4 5.6 5.6 8.0

* Elastic test free height for stainless steel spring washers is subject to bilateral agreement between supplier and buyer per GB 9/T94.1-2008.

Elastic Test Load — GB 9/T94.1-2008 Table 3

Minimum elastic test load (N):

Size (mm) M2 M2.5 M3 M4 M5 M6 M8 M10 M12 M14 M16 M18 M20 M22 M24 M27 M30 M33 M36 M39 M42 M45 M48
Test Load (N) 700 1,160 1,760 3,050 5,050 7,050 12,900 20,600 30,000 41,300 56,300 69,000 88,000 110,000 127,000 167,000 204,000 255,000 298,000 343,000 394,000 457,000 518,000

Material & Mechanical Properties — A4 Stainless Steel (SUS316)

Property Value
Material Grade A4 / SUS316 / 06Cr17Ni12Mo2 / 1.4401
GB Standard Reference GB/T 1220, GB/T 4240
Heat Treatment Annealed — ≥ 34 HRC or 336 HV
Hardness ≥ 34 HRC or 336 HV (per GB 9/T94.1-2008)
Molybdenum (Mo) Content 2.0 – 3.0% — key differentiator vs. A2
Density 7.98 g/cm³
Magnetic Non-magnetic (austenitic)
Operating Temperature -196°C to +400°C
Surface Treatment Simple treatment (whitened & passivated)
RoHS / REACH Compliant

Chemical Composition — A4 Stainless Steel (SUS316 / 06Cr17Ni12Mo2)

Element C (max) Cr Ni Mo Mn (max) Si (max) P (max) S (max)
Content (%) 0.07 16.5 – 18.5 10.5 – 13.5 2.0 – 3.0 2.0 1.0 0.045 0.030

A4 vs. A2 Stainless Steel — Key Differences

Property A4 (SUS316) A2 (SUS304)
Molybdenum (Mo) 2.0 – 3.0% None
Chloride resistance Excellent — seawater & coastal Good — atmospheric only
Acid resistance Superior (sulfuric, phosphoric) Moderate
Pitting resistance High (Mo inhibits pitting) Standard
Max operating temp. +400°C +300°C
Recommended environment Marine, offshore, chemical, food, pool General outdoor, fresh water
Cost Higher (Mo premium) Standard

GB93 vs. DIN 127 — Key Differences

Feature GB 93-1987 DIN 127 Type B
Origin Chinese national standard German DIN standard
Size range M2 – M48 M2 – M80
Dimensional compatibility Largely compatible with DIN 127B for common sizes International reference standard
Common use region China domestic & export to Asia Europe, global industrial
Technical standard GB 9/T94.1-2008 DIN 127 / ISO 3506

How GB93 Lock Washers Work

  • Spring-back tension: The helical split creates a spring that maintains clamp load as the joint settles, compensating for relaxation and embedding losses
  • Bite-in effect: The sharp edges at the split ends bite into both the bearing surface and the nut/bolt head, resisting rotational loosening under vibration
  • Anti-loosening: Friction between the washer and mating parts prevents joint loosening under dynamic and vibration loads
  • Pre-tension: Provides initial pre-tension to maintain connection stability in both static and dynamic conditions

Application Scenarios

  • Marine & offshore structures — hulls, decks, docks, offshore platforms exposed to seawater
  • Coastal & waterfront architecture — railings, facades, bridges in salt-air environments
  • Chemical processing plants — resistance to sulfuric acid, phosphoric acid, and chloride solutions
  • Food & beverage processing — hygienic, easy to clean, no contamination risk
  • Pharmaceutical & medical equipment — high purity, corrosion-free surfaces required
  • Swimming pools & water treatment — chlorinated water resistance
  • HVAC & piping systems — vibration-prone assemblies in corrosive environments
  • GB-standard bolt assemblies — direct replacement for GB93 spring washers in marine-grade applications

Product Photo Gallery

Real product images — FULLERKREG GB93 Lock Washer, A4 Marine Stainless Steel:

[ Photo 1 ] [ Photo 2 ] [ Photo 3 ] [ Photo 4 ]

Packaging & Supply

Size Standard Pack (pcs) Bulk Carton (pcs) Weight per 1000 pcs (approx.)
M3 200 10,000 ~61 g
M4 200 5,000 ~153 g
M5 100 3,000 ~263 g
M6 100 2,000 ~479 g
M8 50 1,000 ~1,091 g
M10 50 500 ~2,101 g
M12 25 500 ~3,580 g
M16 25 200 ~8,313 g
M20 10 100 ~15,351 g
M24 10 50 ~26,755 g

Sizes M27–M48 available upon request. A4 stainless density ≈7.98 g/cm³ — approximately 2% heavier than steel reference weights. Custom packaging and labeling available for OEM / wholesale orders. Contact FULLERKREG for bulk pricing.

Why Choose FULLERKREG?

  • 🏭 Direct manufacturer — factory in China, no middlemen
  • 📐 Strict GB/DIN dimensional control — 100% inspection on critical dimensions
  • 🌍 Global export experience — serving distributors in Europe, North America, Southeast Asia
  • 📦 Flexible MOQ — small trial orders and large bulk shipments both welcome
  • 📋 Full documentation — material certs, RoHS declarations, test reports available
  • ⚡ Fast lead times — standard sizes in stock, ready to ship

Frequently Asked Questions

Q: What is the main advantage of A4 over A2 for GB93 lock washers?
A: A4 (SUS316) contains 2–3% molybdenum, which significantly enhances resistance to chloride pitting, seawater corrosion, and aggressive acids. For marine, coastal, chemical, or pool environments, A4 is the correct choice where A2 would be susceptible to pitting or crevice corrosion.

Q: What is GB93 and how does it relate to DIN 127?
A: GB 93-1987 is the Chinese national standard for helical spring lock washers, equivalent in function to DIN 127 Type B. For common sizes (M2–M48), the dimensions are largely compatible. GB93 is the standard specification for spring washers used in GB-standard bolt assemblies in China.

Q: Is A4 stainless suitable for full seawater immersion?
A: A4 (SUS316) performs well in seawater splash zones and salt-air environments. For continuous full immersion in seawater under high stress, super duplex or higher-grade alloys may be considered for critical structural applications.

Q: Are sizes in parentheses available?
A: Yes. Sizes shown in parentheses (e.g. M14, M18, M22) are non-preferred sizes per GB93 but are available upon request. Please contact FULLERKREG for availability and lead times.

Q: What strength class are these lock washers supplied in?
A: Standard supply is A4-70. A4-50 and A4-80 are available upon request. Please specify your required strength class when ordering.

Q: Are these washers RoHS compliant?
A: Yes. FULLERKREG A4 stainless steel GB93 lock washers are fully RoHS and REACH compliant. Compliance documentation is available upon request.

Q: Do you provide material test certificates?
A: Yes. Mill certificates, chemical composition reports, and dimensional inspection reports are available for all orders upon request.

FULLERKREG Fasteners — Precision GB & DIN Standard Fasteners, Direct from Manufacturer.
For wholesale inquiries, technical questions, or custom orders, please contact our sales team.

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