Over the last five years there have been numerous reports of failures of carbon steel A105 flanges A234 fittings and some A106 seamless pipe. The failure primarily occurred in newly constructed material and the nature of the failures was Brittle Fracture with very low Charpy V-notch values (3 ft-lbs) at room temperatures when the expected notch toughness was higher than 40 ft-lbs. Typically these steels are exempted from impact testing for upto temperatures -20°F (-29°C) per ASME B31.3. It has been found that the cause of low toughness was a gradual change in the chemical composition of the steel during the steel making process primarily low Mn to C ratios (even though within specification limits) addition of alloying elements like boron vanadium kind of heat treatment applied grain size etc.This paper will identify and document how the different factors like low Mn high C addition of boron and resultant grain size affects the impact toughness of steels based on a review of currently available literature. A comparison with impact properties of other product forms of carbon steel like plates etc. will be presented. A review of the current industry best practices and recommendations to avoid brittle fracture due to metallurgical factors without affecting other mechanical properties during hydrostatic testing cold startups and other low temperature in service conditions will be documented and presented.

The heat treatment condition of industrial materials is a critical parameter for material evaluation and its fitness for intended service. Proper heat treatment will produce desired mechanical and physical properties, while absence or improper heat treatment may lead to major failure with huge production, Environmental, Health, and Safety (EHS) impacts. We hereby explain an actual case for cracked gas compressor (CGC) 5th stage discharge line caustic stress corrosion cracking (SCC) that caused unplanned plant shut down and resulted in noticed financial and production loss.
The proven root cause is absence of normalization. Emergency piping batch is received and supposed to be normalized to avoid failure recurrence. Many discrepancies extracted from submitted material certificates, also many physical signs observed on the material itself raising doubts about received material compatibility. Using advanced Positive Material Identification (PMI) device to verify the chemical composition of the received material, results show that the material is questionable.
As a precise test to verify heat treatment condition, microstructure analysis test (metallography) conducted to confirm normalization condition of the material, the resulted grain structure size and growth confirm that one of the received pipes has improper or absence of normalization.
The material rejected as it is proven and confirmed that it is not normalized as per the requirements to avoid further potential of hydrocarbon leakage due to improper material specification. Rejecting the material eliminate the potential of having repeated failure, in addition to 600,000 Saudi Riyal (SR) cost saving as material cost. A common recommendation shared with concerned parties to consider metallography as a mandatory test to be submitted with heat-treated material test certificate (MTC).
Key words: Heat treatment, microstructure, normalization, grain structure, failure, metallography

Boiler system is one of the most critical systems for a utility plant. A utility plant had experienced high percentages of boiler downtime owing to boiler tube sheet cracking failures. Investigations carried out revealed high stress at the tube-to-tube sheet joint in the boiler fire-side entrance. Tube-to-tube sheet joints at the boiler fire-side entrance had been fabricated by strength welding and without any expansion. The strength welded joint had created undue stress leading to cracking of the weld joint by thermal expansion. A higher quality expanded joint consisting of expanding, flaring and seal welding the fire-side entrance was implemented during the re-tube process. The utility plant has now zero downtime due to boiler tube failure. This article summarizes the description and history of failures with the boiler at the utility plant; investigations and corrective actions carried out; and the present improved condition of the boilers.