Search results

This paper aims to evaluate diethylenetriamine (DETA) as an inhibitor on Q235 (Gr. D) steel in ammonia flue gas desulfurization (AFGD) system.

This research was carried out by weight loss, electrochemical measurements, scanning electron microscopy and X-ray photoelectron spectrometry. The effects of DETA on crystallization of ammonium sulfate and its co-crystallization were also investigated by X-ray diffraction and infrared spectroscopy.

The inhibition efficiency of DETA reached a maximum value of 98.96 per cent. DETA is postulated to adsorb on Q235 steel surface, resulting in the formation of a protective film by the accumulation of many flat particles, and the thickness of protective film is 8 μm. DETA had no effect on the crystallization of ammonium sulfate product.

DETA can be used in AFGD system as an inhibitor to protect the equipment well.

This paper aims to study the controlled release and synergistic effect of water-soluble polyvinyl alcohol (PVA) on phosphate corrosion inhibitor at the interface of thermal insulation cotton/carbon steel.

This study was carried out using a coating method, scanning electron microscopy, energy dispersive spectroscopy and AC impedance.

The single-phase phosphate particles were coated/adsorbed on the PVA film, which was formed on the fiber surface of corrosion inhibitor/PVA-impregnated rock wool sample. On the surface of Q235 steel, an effective protective film was formed by the corrosion inhibitor with partially dissolved PVA that can significantly increase the polarization resistance of corrosion reaction, and reduce the capacitive reactance of electric double layer. The rock wool impregnated with the phosphate corrosion inhibitor and 1.5 per cent PVA showed obvious controlled release and inhibition synergism.

The rock wool impregnated with the phosphate corrosion inhibitor and 1.5 per cent PVA showed the following advantages: the adsorption and release quantities of the corrosion inhibitor increased by 3.3 and 2.9 times, respectively; the release-adsorption equilibrium time increased from 2 to 6 h; and the corrosion inhibition efficiency increased from 61.55 per cent to 94.6 per cent.

The purpose of this study was to investigate the reason of G105 coated drill-pipes suffering from washout after drilling for 70000–80000 m.

The microstructure, micromorphology and corrosion products near the washout were analyzed by metallurgical microscopy, SEM and EDS.

Results showed the metallographic microstructure of the material was typical tempered sorbite. No fatigue crack was observed. Drill-pipe washout was caused mainly by the inclusion of MnS in steel because of the excess S and by damaged coating, both of which induced pit nucleation and promoted the pitting corrosion process. The corrosion hole extended from the interior to the exterior, which resulted in the fracturing of the external drill-pipe surface under pressure.

This paper can give practical help to the selection of drill pipe materials in the future.