Author: Amarine Antonio

Shipbuilding and welding professional.
WELDING, WELDING METALLURGYLeave a comment

Blue colour when welding Stainless steel

Amarine Antonio

Oxidation of the root bead and adjacent HAZ during welding of stainless steels is commonly called heat-tint. A chromium-rich scale is formed, which is typically not very protective, and the stainless steel surface becomes chromium-depleted: these effects may impair the corrosion resistance of stainless steel welds. Tests performed in various corrosive environments have shown that susceptibility to pitting and crevice corrosion is greater when the surface is heat-tinted, and the colour of the heat-tint is an indicator of the degree of susceptibility to corrosion. For example, purple-blue oxides are generally the most susceptible to corrosion attack. The critical pitting temperature, … Continue reading Blue colour when welding Stainless steel

WELDING METALLURGYLeave a comment

Hardness test for Duplex, Super duplex

Amarine Antonio

It is sometimes necessary to meet hardness limits for duplex and super duplex stainless steels, and it is convenient to be able to convert between the Rockwell C (HRC) and Vickers (HV) hardness scales. A conversion exists for carbon steel in ASTM E140 but there is no standard conversion for duplex and super duplex grades and the carbon steel conversion has been shown to be inappropriate for these high alloy steels. A correlation between the two hardness scales for duplex and super duplex grades has been developed at TWI from a compilation of data supplied by various organizations. There was … Continue reading Hardness test for Duplex, Super duplex

WELDING, Welding EngineerLeave a comment

Stainless steel become Magnetic (304, 316, 321, 347 series)

Amarine Antonio

Austenitic stainless steels with around 10-12% nickel (e.g. grades 304, 316, 321 and 347) are predominantly non-magnetic due to the face centered cubic (fcc) crystal structure of the austenite phase, which imparts so-called ‘paramagnetic’ (i.e. non-magnetic) behavior. Although a number of second phases, e.g. inclusions or ferrite stringers, may exist in wrought austenitic stainless steel products, the structure is almost exclusively made up of the austenite phase and hence they are essentially non-magnetic. However, weld metals made with filler metal compositions matching the 300 series austenitic steels (e.g. 308, 309, 316 and 347 types) are designed to have a small … Continue reading Stainless steel become Magnetic (304, 316, 321, 347 series)

NDT NDE, OIL & GASLeave a comment

BS 7448 vs ASTM E1820 CTOD fracture test

Amarine Antonio

Both BSI and ASTM have published standards for ‘combined’ fracture toughness test methods, allowing measurement of critical values of stress intensity (K), J and CTOD. The standards cover both ‘single-point’ values of fracture toughness and tearing resistance curves. BS 7448: Fracture mechanics toughness tests, is published in four parts: Part 1: ‘Method for determination of KIc, critical CTOD and critical J values of metallic materials’. Part 2: ‘Method for determination of KIc, critical CTOD and critical J values of welds in metallic materials’ – superseded by BS EN ISO 15653. Part 3: ‘Method for determination of fracture toughness of metallic materials … Continue reading BS 7448 vs ASTM E1820 CTOD fracture test

WELDINGLeave a comment

Heat input vs Arc energy in welding

Amarine Antonio

In arc welding processes, heat input (HI) and arc energy (AE) are both measures of how much energy has been supplied to the workpiece to form a weld. They are both measured in units of energy per unit length. In Europe, this tends to be in kJ/mm, whereas in America it tends to be kJ/in. Arc energy Arc energy is the energy supplied by the welding arc to the workpiece before the efficiency of the process is considered. It is calculated by the following equation: where: V is the voltage used, in volts I is the current used, in amperes … Continue reading Heat input vs Arc energy in welding

Shipbuilding A-ZLeave a comment

EN 287 vs EN ISO 9606

Amarine Antonio

The current status of BS 287-1 and ISO 9606-1 are explained in What is the current status of EN 287-1 and BS EN ISO 9606-1 for welder qualification? Due to this complex situation, it is possible that fabricators will be moving from EN 287 Part 1 to ISO 9606 Part 1, or using the two in parallel, depending on the type of product being manufactured. This means it is necessary to fully understand each standard and the variations between the two. This Job article will provide some insight into the differences between the standards. There are some differences between the two … Continue reading EN 287 vs EN ISO 9606

Welding EngineerLeave a comment

BS EN 287-1 vs BS EN ISO 9606-1 WPQR

Amarine Antonio

ISO 9606-1 has been cited in the Official Journal of the European Union as harmonized with the Pressure Equipment Directive (PED), with effect from 1 March 2018. This FAQ gives a quick summary of the transition between the standards for welder qualification BS EN 287-1 and BS EN ISO 9606-1 and provides recommendations on how to apply them. Please note that this article is not authorized to give official interpretations of BS EN ISO standards and the answer below is an opinion only, and cannot be taken as a definitive answer. No liability rests with this post for any damages … Continue reading BS EN 287-1 vs BS EN ISO 9606-1 WPQR

NDT NDELeave a comment

NDE vs NDT, NDI understanding

Amarine Antonio

Non-destructive testing (NDT) is a testing and analysis technique used by industry to evaluate the properties of a material, component, structure or system for characteristic differences or welding defects and discontinuities without causing damage to the original part. NDT also is known as non-destructive examination (NDE), nondestructive inspection (NDI) and non-destructive evaluation (NDE). Methods of Non-Destructive Testing Current NDT test methods include: Acoustic Emission Testing (AE) This is a passive NDT technique, which relies on detecting the short bursts of ultrasound emitted by active cracks under a load. Sensors dispersed over the surface the structure detect the AE. It is even possible … Continue reading NDE vs NDT, NDI understanding

NDT NDE1 Comment

NDT NDE ASNT Questions and answers for PT, LPI level II (6).

Amarine Antonio

51. Which of the following is the best reason why the application of emulsifier by a brush is not recommended? A. The brushing action mixes the emulsifier with the penetrant prematurely and irregularly, making accurate control of the emulsification time impossible B. Brushing does not always completely coat the part, thereby leaving a portion of the part difficult to wash C. Brushing in itself is not harmful, but many types of brush materials combine with the emulsifier agents resulting in penetrant and part contamination. (answer) D. Brushing results in a streaking appearance during inspection 52. Developing powder should always  be: … Continue reading NDT NDE ASNT Questions and answers for PT, LPI level II (6).