The paper presents a reliability-based approach to assess the structural integrality of tubular joints with cracks in aging offshore platforms. Two different fatigue failure models are established respectively according to crack propagation size and equivalent fatigue strength, and the corresponding computing methods of fatigue reliability are proposed. The fatigue stress of tubular joint suffering sea wave load is calculated by spectrum analysis. The numerical examples are given to show the difference between the two reliability models. Considered the influence of inspection and repair, the reliability is updated by two different maintenance schedules. The analysis results can help to work out the optimal inspection planning, so as to prolong the service life for aged offshore platforms.

Phthalic anhydride switch condenser was imported, failure occurred many times after put in use. There are ellipsoidal winged tubes in them and the holes on tube sheet are ellipsoidal too, which is very difficult to manufacture. Established mathematics model, analyzed the mathematic relation, compiled NC program, realized the numerical controlled process of ellipsoidal hole on MITSUBISHI MCV-1700 machining center, and realized domestic manufacture of phthalic anhydride switch condenser. Analyzed the error of process and selected proper cutter too. Machining center was imported in 1990’s, which CPU is only on 80386 levels, when the NC program is complex, the velocity of calculate will lower than the feed of end mill. The program is compiled with EIA code, which is difficult for most of engineers, took a common PC as program editor to compile program with Quick BASIC, then more technicians can compile program. This improved the procession of process and enlarged the range of machining center.

U shape brass tube bundle on heat exchanger cracked when it was having ammonia leak test. Sample was made from brass tube fragment, polished the surface of the sample, eroded it with solution of 5% iron trichloride (FeCl3) and 10% hydrochloric acid (HCl), then took photos with Nicon-300 metallographic microscope. The fracture is a kind of stress corrosion cracking, the reason of cracking was analyzed. The technology of test was improved, the method should be paid attention to during brass tube exchanger manufacture was given out too.

Tube plate and baffles are all important parts in tubular heat exchangers, drilling holes on them is an important and difficult task for factory. The efficiency of traditional process is low and the error is big. Analyzed the holes’ distributing on six shell side routes exchangers, established mathematics model, compiled numerical controlled program with EIA code, realized numerical controlled process of tube plate and baffles on MITSUBISHI machining center. This improved the quality of equipment and lowered the cost.

In this paper, SEM, EPMA, and micro shear experimental method were applied to analyse the structure, inclusion morphology and composition, micro-area strength and toughness of the X70 pipeline steel girth weld joint. The results show that inclusions are mainly nonmetallic oxides, sulfides and calcium compounds. The length of inclusions can be up to 1mm, which have substantially reduced the strength and toughness of weld joint. By the combining effect of internal and external force, cracks tend to initiate around inclusions and propagate along the direction of inclusions, and finally reduce the impact toughness of girth weld.