Failure Analysis of 90-10 Cu-Ni Pipe
Presented herein is a report on the analysis of the cracking failure of several lengths of 6.65 in OD 90-10 Cu-Ni pipe.

Failure Analysis of a Gas Well Production Tubing
The gas well under consideration with a total depth of 18,000 ft; bottom-hole temperature of approximately 350 F, while bottom-hole pressure was measured as 10,000 psi. Hydrogen sulfide content of the gas varied from 14 to 18 ppm, which is equivalent to an H₂S partial pressure of 0.14 to 0.18 psia.

Failure Analysis of 13Cr Production Tubing
Examination of pitted production tubing showed that pitting initiated on scratches on the inner surface of the pipe. Presumably, the abraded areas were caused by a wireline or similar workover procedures. The pitting corrosion propagated due to contact with produced water that contained chlorides and that was in equilibrium with produced CO₂. An inhibitor treatment after workover would help alleviate similar problems.

Failure Analysis of a Safety Relief Valve Spring
A safety relief valve failed due to corrosion fatigue. The fracture initiated at a corrosion pit and was accelerated by sulfide stress cracking and the presence of a decarburized surface layer on the spring. The H12 tool steel spring alloy is unacceptable for sour service; it should be replaced by a material with good corrosion and H₂S resistance.

Failure Analysis of ERW Pipe Burst
The catastrophic burst of a piece of LS-125 ERW pipe was attributed to weld defects and low toughness along the fusion line. The fracture initiated at an ERW weld defect on the pipe inner surface. The microstructure was normal for quenched and tempered low alloy steel. Transverse mechanical properties across the ERW weld fusion line showed acceptable yield and tensile strengths but poor ductility.

Failure Analysis of Stopple Plug
In April, 1990, a stopple plug installation failed at an oil refinery. It was installed in a 10-inch pipeline which contained premium gasoline without MTBE additive. The reported process conditions in the line at the time of failure was a gasoline pressure of 375 psi at ambient temperature. The stopple failed after only five (5) hours of service. The adjacent stopple installation in the line successfully held pressure for 24 hours without failure. Both stopple sealing elements were reported to be Buna-N. The size of the sealing elements (or plugs for simplicity) were measured to be 10.5-inch O.D.

Failure Analysis of Stainless Steel Isobutane Piping
Failure investigation and analysis was undertaken on two (2) samples of 304L stainless steel pipe. This pipe was removed from service during a plant outage. The pipe had been in recycle isobutane service. The investigation included location and documentation of pitted areas on the pipe, gross analysis of scale and other deposits on the pipe interior surface, and a report on what caused the corrosion.

Failure Analysis of an HTC Reactor
The leak which occurred in an HTC Reactor on February 7, 1991, was the result of rapid corrosion of the 405 SS cladding and the steel shell by a bubble of hot chlorine gas. Carbon plugging of the static mixer prevented normal circulation of the reactor liquid and allowed the chlorine bubble to accumulate and attack the mixer and the vessel wall.

Failure Analysis of a Steel Low Pressure Steam Line
Cracking of an 18-inch steel steam line to the caustic heater has been determined to be due to stress corrosion cracking. The cracking originated on the inner surface as the result of accumulation of caustic boiler water salts in the line.

Storage Tank Corrosion Evaluation
A corrosion related failure of a steel storage tank is thought to be related to water contamination of the tank's contents. Water contamination occurred because the tank had a floating roof which allowed rain water, falling on top of the tank, to mix with the tank's contents.

Failure Analysis of High Strength Bolts
A number of 2-inch strength bolts have failure in less than one (1) year due to corrosion fatigue. These bolts are on the clamps fastening the subsea storage tank to anchor piling. Wave action and shallow gulf sea water provided the cyclic stresses and corrosion environment. The short life of the bolts is attributed to their being insufficiently tightened.

Catalytic Oxidation Reactor Failure Analysis
A Catalytic Oxidation Reactor developed a leak in service. A small hole penetrated the vessel wall. The leak was attributed to corrosion by high temperature hydrochloric acid when a steam leak occurred in the reactor.

Coiled Tubing Failure Analysis
A section of CYMAX 100 grade coiled tubing from a well in South Pass 89 oil field parted in service. The cause of the tubing failure was a result of tensile overload.

Compressor Piston Rod Failure Analysis
A failure analysis was done on a fractured piston rod from the Ingersoll-Rand C-1550 compressor. The rod failed due to mechanical fatigue, originating in the root of threads cut on the rod piston end.