420 Bar SAE Staple-lock fittings and adapters for hydraulic power-transmission circuits.Such equipment is primarily used in high pressure applications within the mining industry.
The Technical Reference document is intended to add clarity to some design aspects of 420 bar Super Staple-Lock Fittings and Adapters. this document is assisted with information from DIN 20043 “Staple-Lock Couplings for Hydraulic transmission Circuits”, SAE J 1467 “Clip Fastener Fittings”, NCB 638 and BS 6537 “Specification for staple type connectors for hydraulic fluid power application”.
This document defines:
1. minimum working pressure of the assembled fitting (including its staple)
2. relevant testing and conformance standards
3. arrangement of components & their individual dimensions
4. material specifications for the components
5. corrosion resistance of metal components
6. identification
7. minimum burst pressure
8. impulse requirements of the assembled fitting
Minimum working pressure
Table 1 Minimum working pressure of the assembled Super staple-lock fitting. This table is based on 4:1 FOS per ISO 7751 “Rubber and plastic hoses and hose assemblies. Ratios of proof and burst pressure to design working pressure.”
Nominal size DN Maximum Working Pressure bar
25 420
32 420
40 420
50 420
Relevant standards
ISO 471 Rubber: Temperature, humidities and times for conditioning and testing.
ISO 1043-1 Plastics Symbols and abbreviated terms Part 1 Basic polymers and their special characteristics. Refer to this standard for Back-up Rings.
ISO 1629 Rubber and lattices Nomenclature refer for O-Rings (also ref DIN 3771-4 “Fluid systems; O-rings; quality acceptance criteria”).
ISO 1402:1994 Rubber and plastic hoses and hose assemblies Hydrostatic testing. Refer to for hydrostatic testing.
ISO 6803: 1994 Rubber and plastic hoses and hose assemblies Hydraulic-pressure impulse test without flexing. Refer for hydraulic pressure impulse test without flexing.
ISO 7751:1991 Rubber and plastic hoses and hose assemblies. Ratios of proof and burst pressure to design working pressure. Refer to for ratios of proof pressure to design working pressure.
ASTM B117 Salt spray testing Refer to for methods of salt spray (fog) testing.
Description of Super staple-lock fittings assembly
Dimensional details of male Super Staple Lock fittings coupler
Dimensional details of female Super Staple Lock fitting coupler
Dimensional Details of Staple
Dimensional details of O-Ring
Dimensional details of O-Ring Back-up washer
Minimum burst pressure of assembly
Materials
The male staple-lock nipple shall be manufactured from 1.0718 steel per EN10277-3 (Bright steel products. Technical delivery conditions. Free cutting steels), minimum tensile 345 Mpa, minimum UTS 200 Mpa.
The female staple-lock adaptor shall be manufactured from 1.0718 steel per EN10277-3 minimum tensile 345 Mpa, minimum UTS 200 Mpa.
Note: All male and female 420 bar rated nipples and couplers shall be constructed from one (1) piece forgings, cold headed or machined from bar stock. Fittings fabricated from multiple components are not permissible without written approval by customer’s engineers.
The staples shall be manufactured from Stainless Steel.
Stainless steel staples shall be manufactured from 420S45 stainless steel The hardness of the staples shall be Rc28 +/- 3
The O-ring shall be manufactured per ISO 1629 “Rubber and lattices – Nomenclature” and made from Nitrile (NBR) rubber having a Shore A hardness of 88 +/- 3 unless otherwise specified
The O-ring Back-up washer shall be manufactured per ISO 1043-1 and made from a Polyamide, such as Teflon (PTFE), Acetal homopolymer
Corrosion resistance (of metal components)
When the assembled male nipple, female coupler & staple are salt spray tested in accordance with ASTM B117 “Salt spray testing”. A minimum of 400 hrs (before red rust) shall be required
Burst
Minimum burst qualification of the assembled male nipple (c/w O-Ring, backup washer), female coupler and staple shall be per table 7, when tested per ISO 1402 “Rubber and plastic hoses and hose assemblies – Hydrostatic testing”
Minimum burst pressure of assembly
Nominal size DN Minimum Burst Pressure bar
25 1680
32 1680
40 1680
50 1680
Impulse
Minimum qualification requirement is 500,000 impulse cycles at 1.33 times max rated pressure (i.e. 560 bar) per ISO 6803 “Rubber and plastic hoses and hose assemblies Hydraulic pressure impulse test without flexing”is required per assembly size.
