مجله دانش آزمایشگاهی ایران
پیاپی 44 (زمستان 1402)

An APM strategy can offer a more advanced, holistic approach to efficient asset usage. APM uncouples the pressure, leading to increased availability and utilization of lab assets and improved efficiency. This approach affords unprecedented visibility and asset control while reducing costs and increasing sustainability.

This research focuses on the investigation and estimation of the remaining life of ASTM A106 Grade B steel pipes. The examined pipes have been in service for 7 years at a temperature of 280 degrees Celsius and a working pressure of 61 bar, conveying mostly methane as the fluid. Various tests including thickness measurement, chemical composition analysis, examination of microstructure using optical microscopy and scanning electron microscopyenergy dispersive X-ray spectroscopy, tensile testing at ambient and elevated temperatures, and macrohardness testing were conducted to estimate the remaining life. According to the obtained results, all samples exhibited a ferrite-pearlite microstructure, and no significant reduction in the thickness of the examined specimens was observed. Moreover, considering the current operational conditions, it is concluded that the pipes are in good condition for service for an additional 7 years with a confidence level of 4.99%.

In this study, the elbow joint of a natural gas pipeline at a 90-degree angle was investigated at the pressure reduction station. Despite not being in operational conditions, a longitudinal crack appeared in the joint after welding operations. To identify the factors leading to joint degradation, tests such as fracture testing, examination of the macroscopic crack structure, chemical composition analysis using quantum testing, optical microscopy, scanning electron microscopy, X-ray energy dispersive spectroscopy, macrohardness testing, and tensile testing at ambient temperature were conducted. Based on the analysis of the results and modeling performed on the joint, the primary factor contributing to crack formation is attributed to issues in the construction stages and residual stresses resulting from welding operations. The increase in hardness near the crack indicates the influence of residual stresses on the microstructure of the joint during welding operations. This also results in localized reduction in mechanical strength. Consequently, flaws, weaknesses in the microstructure, and microscopic cracks were observed in the images obtained from optical and electron microscopy. Therefore, it can be concluded that the examined joint has become sensitive due to the welding process and is subjected to residual stresses.

Hydrocarbons analysis is important in the oil and gas industry, as stream composition has a strong impact on plant operations. The composition of hydrocarbon streams vary across a plant, which makes the selection of analytical methods challenging. Traditional methods for the evaluation of liquid hydrocarbon streams include the Detailed Hydrocarbon Analysis (DHA); however, non-traditional methods, such as comprehensive gas chromatography (GCxGC), are also utilized in the chemical industry. This work details a comparison of analytical techniques available for such analyses, specifically, DHA and GCxGC compared to the recently introduced GC-Vacuum Ultra Violet (GC-VUV) system. Numerous liquid hydrocarbon streams were blended together to generate a composite and extensive matrix in terms of composition. Paraffin, iso-paraffin, olefin, naphthene, and aromatic (PIONA) results are presented for the three techniques. All of those methods obtained relative standard deviations lower than 1.3% for five injections a day for three days. Standard addition curves were utilized to accurately quantify specific compounds in a liquid hydrocarbon stream, and these results were compared to the GC-VUV PIONA+ and DHA quantification procedures.

Most of the time, it is assumed that the abundance ratio of natural isotopes is constant, but when this ratio is measured very precisely, it shows significant changes. It should be noted that the isotope ratio mass spectrometer is able to determine the ratio of stable isotopes very accurately and precisionly, so that by checking the isotope ratio of the elements carbon, hydrogen, oxygen, nitrogen and sulfur using an isotope ratio mass spectrometer, it is possible to fingerprint food made by different manufacturers and as a result to track and control the authenticity of food and especially detect fraud in food products.

Food allergens, responsible for IgEmediated allergic responses and listed in European, North American and Japanese regulation, are exclusively proteins and are ideally detected by analytical methods targeting either peptides or proteins. However, in some cases where no suitable methods for proteins exist or as an alternative method to substantiate results from protein- based methods, DNA-targeting methods can be used as indicators of the presence of potentially allergenic proteins. The advantage of DNA-targeting methods like PCR, real-time PCR is presently the lower cost and availability of free literature on several detection systems, including a certain degree of multiplexing. Clear disadvantages include the poor sensitivity for egg, milk and samples containing inhibitors (like polyphenols in chocolate) as well as its limited applicability in some industrial protein concentrates. In addition, if quantitative results need to be obtained, the DNA-based system needs to be calibrated for each matrix tested, as protein-to-DNA composition is typically matrix specific. However, PCR based methods are well established in many laboratories and still regularly used. This chapter discusses suitable systems for detection of DNA of ingredients and foods containing allergenic proteins, potential pitfalls and multiplex capabilities of such systems.