Table of Contents
- 1 What is RT1 RT2 RT3 RT4 radiography?
- 2 What does full radiography mean?
- 3 How do you calculate joint efficiency factor?
- 4 What is a Type 1 weld?
- 5 What do you know about radiography?
- 6 What is weld efficiency?
- 7 What is joint efficiency factor?
- 8 What is a joint factor?
- 9 What’s the difference between 100% RT and full radiography?
- 10 How is spot radiography used to improve joint efficiency?
- 11 Which is the minimum distance for radiographic testing?
What is RT1 RT2 RT3 RT4 radiography?
As per ASME, there are four types of Radiography test (RT), i.e. RT1, RT2, RT3 and RT4. Joint efficiency is the number used to define welded joint strength which basically depends on the RT type. For RT1 and RT2 joint efficiency is 1.0, for RT3 efficiency is 0.85 and for RT4 efficiency is 0.70.
What does full radiography mean?
Full radiography is equivalent to RT-1 stamping as defined in UG-116. As you can see, butt welds in small (not exceeding 10″), thin wall nozzles are not required to be RTed. 100% RT means all butt welds, including those in small nozzles will have radiography examination in full length.
What is the difference between Rt-1 and Rt 2?
The RT-1 plan requires all butt-welded joints be fully radiographed over their entire length using the criteria in paragraph UW-51. The RT-2 plan requires all category A and D butt-welded joints be radiographed over their entire length using the criteria in paragraph UW-51.
How do you calculate joint efficiency factor?
It is also a way to introduce safety factors in welding of shells for containment, and can be expressed as follows: Joint Efficiency = Strength of weld/Strength of base material.
What is a Type 1 weld?
Definition of Type (1): Welds using metal backing strips which remain in place are excluded. Efficiency: is 1, 0.85 or 0.7 depending upon the degree of radiography applied. A long seam welded from one side with no backing strip – always Type 1.
In which type of joint radiography is done?
Radiographic testing can provide a permanent film record of weld quality that is relatively easy to interpret by trained personnel. This testing method is usually suited to having access to both sides of the welded joint (with the exception of double wall signal image techniques used on some pipe work).
What do you know about radiography?
Radiography is a health care science occupation dealing with medical diagnostic images. During training, students are exposed to all facets of health care.
What is weld efficiency?
Joint Efficiency refers to the strength of a welded joint with respect to the strength of the base metal. A Joint Efficiency of 1.00 indicates that the weld has the same strength of the base metal, and it is assumed as if it is seamless. Its strength should be more than or equal to the strength of the base metal.
What is an ASME U stamp?
The U-Stamp represents ASME’s section VIII Division 1; rules for the construction of pressure vessels. In order to obtain the U-Stamp, Sweco Fab was required to meet ASME’s guidelines for the design, fabrication, inspection, and testing of Pressure Vessels.
What is joint efficiency factor?
Joint Efficiency refers to the strength of a welded joint with respect to the strength of the base metal. Concurrently, an efficiency of 0.50 indicates that the joint has half the strength of the base metal. Joint efficiency is an important factor to be considered in the design stage.
What is a joint factor?
In welding, the ratio of the strength of a joint to the strength of the base metal; expressed in percent.
What is ASME W stamp?
ASME Stamp means the symbol used to designate that the container has been built to the American Society of Mechanical Engineers (ASME), Boiler and Pressure Vessel Code, Section VIII, Divisions 1 or 2, Rules for the Construction of Unfired Pressure Vessels.
What’s the difference between 100% RT and full radiography?
As you can see, butt welds in small (not exceeding 10″), thin wall nozzles are not required to be RTed. 100% RT means all butt welds, including those in small nozzles will have radiography examination in full length. This is not a code requirement. It is usually a service requirement. Vessels in wet H2S service often require 100% RT.
How is spot radiography used to improve joint efficiency?
Since circumferential stress governs cylindrical shell design, performing spot radiography on long seams is the easiest way to improve joint efficiency and thus reduce shell thickness. When specified, spot radiography requires one examination for every 50 feet of the same type of weld, with the provision that each welder’s work is represented.
Is it mandatory to do full radiography in butt welds?
In items 1, 2 and 3 it is mandated by code; to do full radiography in all butt welds in vessel so it means it is mandatory for designer to select column (a) in UW-12 table. But in item 4, there is no mandating rule.
Which is the minimum distance for radiographic testing?
According to geometric unsharpness formula (Ug = f *OFD/FOD) for minimizing the Ug value, OFD value shall be minimizing therefore object to film distance shall be minimum. Source to object distance (SOD) shall be set according radiographic technique, object shape and strength of source.