ISO 13902:1997

Overview

ISO 13902:1997 specifies a laboratory method for the determination of high sulfur content in steel and iron by combustion in a high‑frequency induction furnace with subsequent infrared (IR) absorption measurement of the evolved sulfur dioxide (SO2). The procedure is applicable to sulfur levels between approximately 0.10 % (m/m) and 0.35 % (m/m) and includes sample preparation, combustion, IR analysis, calibration and quality checks.

Key topics and technical requirements

• Principle: Combustion of a weighed test portion in pure oxygen in an induction furnace → sulfur to SO2 → measurement by IR absorption.
• Analytical range: Method targeted at relatively high sulfur contents (around 0.10–0.35 % m/m). Calibration series extend to higher calibration members for instrument response.
• Reagents & materials:
  • Oxygen, minimum purity 99.5 % (m/m); use an oxidation catalyst (CuO or Pt) and purification if organics suspected.
  • Pure iron with sulfur < 0.0005 % (m/m) as diluent/blank material.
  • Accelerator: tungsten free from sulfur (or known < 0.0005 % S).
  • Anhydrous barium sulfate (≥ 99.5 %), dried at 105–110 °C for 3 h for calibration spikes.
  • Magnesium perchlorate and inert ceramic (attapulgus clay impregnated with NaOH) for gas drying/purification; specified particle sizes.
• Apparatus:
  • High‑frequency induction furnace (silica tube within induction coil), IR gas analyser (continuous flow or collected gas mode), microbalance (0.001 mg), ceramic crucibles and pre‑treated filters/crucibles (e.g., crucibles ignited at 1 100 °C).
• Calibration & quality control:
  • Use barium sulfate standards in a multi‑point calibration graph; perform duplicate blank tests and determine sulfur in the pure iron.
  • Precision verified by interlaboratory trials; repeatability and reproducibility limits are reported in the standard.
• Safety: Emphasis on burn hazards, oxygen handling and removing excess oxygen from apparatus.

Applications and users

• Routine quality control and acceptance testing in steel mills and foundries.
• Material certification and chemical composition analysis laboratories for ferrous products.
• Metallurgical process control where monitoring relatively high sulfur is critical (e.g., alloy design, desulfurization effectiveness).
• Instrument manufacturers and service labs implementing or validating induction‑combustion IR analyzers.

Related standards

• ISO 14284 - Sampling and preparation for chemical composition.
• ISO 565 - Test sieves (500 μm) for powder fractionation.
• ISO 5725‑1/2/3 - Accuracy (trueness and precision) of measurement methods and results.

Keywords: ISO 13902:1997, sulfur determination, infrared absorption, induction furnace, steel and iron, combustion analysis, SO2 measurement, calibration, quality control.