ISO 6305-4:1985

Overview

ISO 6305-4:1985 - Railway components - Technical delivery requirements - Part 4 defines product quality and acceptance conditions for untreated steel nuts and bolts and high‑strength nuts and bolts used for fish‑plates and rail fastenings. The standard covers manufacturing rules, dimensional and threading requirements, mechanical testing and acceptance sampling, markings, purchaser data, and packaging. Annexes A–D provide progressive (Wald) sampling plans for lot inspection.

Key Topics and Requirements

• Scope and classes: Specifies quality classes (examples shown in the standard include 4.6, 5.6, 6.8, 8.8, 10.9) and refers to mechanical property requirements in ISO 898‑1 (bolts) and ISO 898‑2 (nuts).
• Manufacturing: Bolts must be manufactured in one piece (no welding); heads and nuts may be forged or cold‑formed. Steelmaking and heat‑treatment processes are supplier‑chosen but must be declared to the purchaser on request.
• Dimensions & threads: Conformance with applicable international standards for metric threads and tolerances; purchaser supplies final drawings and thread type. Tolerances follow ISO 4759‑1; thread tolerances per ISO 965‑1 when specified.
• Mechanical tests: Tests on finished parts per ISO 898 series. Includes proof load and hardness tests for nuts, tensile and proof load tests for bolts, and a screwing test (hand‑fit then torque): maximum allowed torque is specified (e.g., 35 N·m for bolts ≤20 mm and 45 N·m for bolts >20 mm).
• Acceptance & sampling: Lotting rules: fish‑plate bolts (lots 500–20,000 pieces), fastening bolts (lots 2,000–100,000). Sampling may use the progressive Wald plan (Annexes A–D) or ISO 2859 sampling tables; statistical acceptance criteria and producer/user risks are defined.
• Marking & documentation: Markings must be legible in relief or recess per purchaser drawings. Purchaser must provide drawings, usage conditions, and packaging requirements. Control‑chart (control‑card) inspection procedures may be accepted by the purchaser.
• Packaging & records: Packaging to purchaser specification; manufacturing and inspection records must be retained (standard specifies minimum retention until 31 December of the year following manufacture).

Applications and Users

• Rail infrastructure designers, track engineers, and procurement/specification teams specifying bolts and nuts for rail joints and fastenings.
• Manufacturers and suppliers of railway fasteners who need to meet delivery and acceptance conditions.
• Quality assurance and inspection personnel responsible for lot sampling, mechanical testing, and conformity assessment for rail components.
• Contracting authorities and rail networks specifying purchase drawings, thread classes, mechanical classes, and packaging.

Related Standards

• ISO 898‑1 (mechanical properties of fasteners - bolts, screws)
• ISO 898‑2 (nuts with proof load)
• ISO 965‑1 (metric thread tolerances)
• ISO 4759‑1 (fastener tolerances)
• ISO 2859 (sampling procedures for inspection by attributes)

Keywords: ISO 6305‑4:1985, railway components, nuts and bolts, fish‑plates, fastenings, high‑strength bolts, technical delivery requirements, sampling plan, mechanical tests.