This article is about Welding Engineer Question Answers as per international codes and standards.
Welding Engineer Question Answers
1) What is PMI?
PMI stands for Positive Material Identification. It is a verification process to ensure that the nominal chemical composition of an alloy material is as specified and ordered. PMI is typically performed using portable handheld analyzers that utilize technologies such as X-ray fluorescence (XRF) or optical emission spectroscopy (OES) to analyze the elemental composition of the material. By comparing the measured composition with the specified composition, PMI helps to ensure that the correct materials are being used in construction or manufacturing processes, preventing potential issues related to material substitution or quality.
2) What are the gauges used for fit up?
For fit-up inspections, various gauges can be used to check the alignment and dimensions of the components. Two commonly used gauges are:
- Bridge cam: It is a measuring tool used to check the gap between two adjacent components. The bridge cam is placed across the gap, and its measurement scale allows the inspector to determine if the gap falls within the acceptable range.
- High-Low gauge: This gauge is used to measure the variation in the height or level of two adjacent components. It consists of two pins or probes that can be adjusted to match the reference height. The inspector places the pins on the components and checks if they are within the specified tolerance range.
These gauges help ensure that the fit-up of components meets the required specifications and allows for proper welding or joining.
3) What material is used for drinking water service?
In the context of drinking water service, materials that are commonly used include:
- Copper: Copper pipes and fittings are often used for drinking water supply lines. Copper is durable, corrosion-resistant, and has antimicrobial properties.
- PEX (cross-linked polyethylene): PEX pipes are flexible and widely used for both hot and cold water distribution systems. PEX is resistant to corrosion and scale buildup.
- CPVC (chlorinated polyvinyl chloride): CPVC pipes are suitable for hot and cold water applications. They offer good chemical resistance and are easy to install.
- Stainless steel: Certain grades of stainless steel are suitable for drinking water service due to their corrosion resistance and hygienic properties.
It’s important to adhere to local regulations and standards when selecting materials for drinking water service to ensure they meet the required safety and health standards.
4) What are the types of bolts and specifications?
There are various types of bolts used in different applications, and their selection depends on factors such as the environment, load requirements, and material compatibility. Two common types of bolts and their specifications include:
- A193 B7: This specification covers alloy steel bolting materials for high-temperature or high-pressure service. A193 B7 bolts are commonly used in applications that require high strength and resistance to heat and corrosion.
- A320 B8: This specification covers stainless steel bolting materials for low-temperature service. A320 B8 bolts are suitable for applications where low-temperature resistance and corrosion resistance are required.
SAES-L-109 is a specific specification or standard related to bolts that may be applicable in a particular project or industry. The exact details of this specification should be referred to for specific requirements.
5) What is color coding?
Color coding is a system used for marking piping bulk materials to identify the material, contents, or purpose of the pipes. It helps in visual identification and assists in distinguishing different types of pipes and their applications. The color coding scheme may vary depending on industry standards and project requirements. Commonly used color codes for piping materials include:
- Yellow: Gas lines
- Green: Sewage or drainage lines
- Blue: Water lines
- Red: Fire protection lines
- Gray: Electrical lines
- White: Steam lines
Color coding is an effective visual aid for quick identification of pipes and helps in preventing errors.
6) What are the different sections of the ASME code? Where are these sections referred?
The ASME (American Society of Mechanical Engineers) code consists of various sections, each focusing on different aspects of engineering and construction. Here are the different sections of the ASME code and where they are referred to:
A. ASME Section I: This section provides rules for the construction of power boilers. It is referred to when designing and constructing power boilers.
B. ASME Section II: This section covers materials. It is divided into several parts, including ferrous materials (Part A), non-ferrous materials (Part B), specifications for electrodes and filler wire (Part C), and properties (Part D). It is referred to when selecting and specifying materials for construction.
C. ASME Section IV: This section provides rules for the construction of heating boilers. It is referred to when designing and constructing heating boilers.
D. ASME Section V: This section deals with non-destructive examination methods. It is referred to when performing inspections and testing using non-destructive examination techniques.
E. ASME Section VI: This section offers recommended rules for the care and operation of heating boilers. It provides guidelines for the safe and efficient operation of heating boilers.
F. ASME Section VII: This section provides recommended guidelines for the care of power boilers. It offers guidance on the maintenance, operation, and safety practices for power boilers.
H. ASME Section VIII: This section contains rules for the construction of pressure vessels. It is divided into Division I and Division II, and it is referred to when designing and constructing pressure vessels.
I. ASME Section IX: This section deals with welding and brazing qualification. It provides requirements for qualifying welding and brazing procedures and personnel.
7) What types of PMI machines are available?
PMI (Positive Material Identification) machines are used for verifying the chemical composition of alloy materials. Two commonly used types of PMI machines are:
- X-Ray Fluorescence (XRF): XRF analyzers use X-ray radiation to excite the atoms in a material, causing them to emit characteristic fluorescent X-rays. By measuring the emitted X-rays, the elemental composition of the material can be determined. XRF machines are portable and offer quick results.
- Optical Emission Spectroscopy (OES): OES analyzers use a high-frequency spark to excite the atoms in the material, causing them to emit light at specific wavelengths.
8) What type of cutting is used for stainless steel? What are the types of grinding wheels and how to identify them?
For stainless steel cutting, one commonly used method is:
- Plasma arc cutting: Plasma arc cutting involves using a high-velocity jet of ionized gas (plasma) to melt and remove the metal. It is a fast and precise cutting method suitable for stainless steel and other metals.
Regarding grinding wheels, there are different types available, and they can be identified by various means, including:
- Types of grinding wheels: Common types of grinding wheels used for various applications include iron oxide wheels, zirconium wheels, and aluminum oxide wheels. These wheels have different compositions and properties that make them suitable for specific grinding tasks.
- Identification by color coding: In some cases, grinding wheels may be color-coded to indicate their type or characteristics. For example, blue-colored grinding wheels are often used for certain applications. However, it’s important to note that color coding practices may vary, and it is recommended to consult the manufacturer’s specifications or guidelines for accurate identification.
9) Name the different types of service conditions.
The different types of service conditions in the context of piping and equipment refer to the operating conditions under which they are designed to operate. The main factors that define service conditions are:
- Temperature: The temperature at which the system or equipment will operate, including normal operating temperature and potential temperature variations.
- Pressure: The pressure level, including operating pressure, maximum allowable pressure, and potential pressure fluctuations.
- Fluid type: The nature of the fluid being transported or processed, such as water, steam, gas, oil, chemicals, etc. Different fluids may have different properties and requirements.
These service conditions play a crucial role in determining the material selection, design, and construction of piping systems and equipment to ensure their safe and reliable operation.
10) What are the acceptable branch connections and fittings? Also, mention limitations.
Acceptable branch connections and fittings depend on various factors and considerations. However, some general guidelines and limitations include:
- Branch connections should not create dead legs: Dead legs are sections of piping that do not have proper flow and can lead to stagnant fluid and potential corrosion issues. Branch connections should be designed to avoid dead legs and ensure proper flow and circulation.
- Branch connections 4 inches and smaller should be spaced adequately: Branch connections, such as drain and vent valves and drip legs, which are 4 inches and smaller in size, should be spaced a minimum horizontal distance of 24 inches from fixed supports or obstructions. This spacing helps ensure accessibility and ease of maintenance.
It’s important to note that specific design requirements and limitations may vary depending on industry standards, project specifications, and regulatory requirements. Proper engineering practices, along with adherence to applicable codes and standards, should be followed to determine the acceptable branch connections and fittings for a particular application.
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