A kiln, 7.6 m (25 ft) long with a 1 m (3 ft) internal diameter and a 6.3 mm (0.25 in.) wall thickness, is used to regenerate spent charcoal returned by water utilities. This charcoal contains up to 0.57% S and 2.04% Cl. The kiln is made of Inconel 601 (N06601) welded using Inconel 617 (N06617) as a filler alloy. Wet charcoal is fed in at one end of the kiln and travels while being tumbled within the inclined rotating vessel. Temperatures range from 480 deg C (900 deg F) (Zone 1) to 900 deg C (1650 deg F) (Zones 2 and 3). Steam is introduced at the discharge end at 95 g/s (750 lb/h), 34 to 69 kPa (5 to 10 psi), and 125 deg C (260 deg F). The kiln developed perforations within eight months of operation. Investigation (visual inspection, metallurgical analysis, energy-dispersive spectroscopy, and 44X micrographs) supported the conclusion that the sulfur and chlorine in the charcoal attacked the Inconel 601, forming various sulfides and chlorides. Recommendations included on-site testing, and installation of test coupons of various alloys before fabricating another kiln. The suggested alloys were RA85H, 800HT, HR-120, Haynes 556, and HR-160.

An alloy IN-690 (N06690) incinerator liner approximately 0.8 mm (0.031 in.) thick failed after only 250 h of service burning solid waste. Investigation supported the conclusion that the root cause of the failure was overfiring during startup and sulfidation of the nickel-base alloy. No recommendations were made.

Persistent leakage was experienced from copper tube heaters which formed part of dairy equipment. Metallurgical examination of the brazed joints showed them to have suffered a preferential corrosion attack. This resulted in the phosphide phase of the brazing alloy being corroded away, leaving a weak, porous residual structure. The brazing alloy was of type CP 1 as covered by BS 1845. Header and tube materials were basically copper-nickel alloys for which the use of a phosphorus bearing brazing alloy is not recommended owing to the possibility of forming the brittle intermetallic compound, nickel phosphide. The use of a brazing alloy containing phosphorus was unsuitable on two counts and a quaternary alloy containing silver, copper, cadmium and zinc, such as those in group AG1 or AG2 of BS 1845 would be more suitable. However, because corrosive problems experienced in these units indicated severe service conditions, a proprietary alloy similar to AG1, but containing 3% nickel, was recommended.