Visual Testing Quiz

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محمد فضل هاشمی: قتل سلوان مومیکا اقدامی ”مذموم و غیر قابل دفاع” است

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۱۱ بهمن ۱۴۰۳ · محمد فضل هاشمی استاد فلسفه و الهیات در دانشگاه اپسالا می‌گوید قتل سلوان مومیکا در واقع به نحوی اعدام وی بود که بصورت زنده در رسانه‌های

Prior to welding, some typical action items requiring attentionby the visual inspector should includethe following:

(1) Review drawingsand specifications

(2) Check procedureand performance qualifications

(3)Establish holdpoints if required

(4) Establish documentationplan

(5) Review material documentation

(6) Examine basematerial

(7) Examine fitup and alignment

of joints

(8) Review storageof welding consumables

During welding, some typical action items requiring attention by those responsible for weld quality should include thefollowing:

(1) Check preheat and interpass temperatures

(2) Check conformance Specification (WPS) to Welding Procedure

(3) Examine weld root pass

(4)Examine weld layers

This alsoprovides a check to determineif adequate cleaning is being accomplished between passes. This may help toalleviate the occurrenceof slag inclusions in the final weld.

(5) Examine second side prior to welding Any of these factors, if ignored, could result in discontinuities that could cause serious quality degradation.

Critical joint root conditions may exist on the second side of a double-welded joint. This area should be examined after removal of slag and other irregularities. This is to assure that all discontinuities have been removed and that the contour of the excavation provides access for subsequent welding.

After Welding. Following welding, some typical action items requiring attention by the visual inspector should include the following:

(1) Examine weld surface quality

(2) Verify weld dimensions

(3) Verify dimensional accuracy صحت ابعادی

(4) Review subsequent requirements الزامات بعدی

Porosity is a cavity-type discontinuity formed by gas entrapment حبس گاز during solidification انجمادسازی  or in a thermal-spray deposit. The discontinuity formedis generally spherical and may be elongated. A common cause of porosity is contamination during welding.

piping porosity which is a form of porosity having a length greater than its width that lies approximately perpendicular to the weld face. Piping porosity may also be referred to as wormhole porosity.

Aligned Porosity

The pores may be spherical or elongated. Aligned porosity is sometimes referred to as linear porosity.

Undercut is generally associated with either improper welding techniques or excessive welding currents, or both.

Incomplete fusion the result of improper welding techniques, improper preparation of the base metal, or improper joint design 

Incomplete joint penetration may result from insufficient welding heat, improper joint design (e.g., thickness the welding arc cannot penetrate),or improper lateral control of the welding arc 

Underfill is a conditionin which the weld face or root surface of a groove weld extends below the adjacent surfaceof the base metal. It results from the failure of the welder to completely fill the weld joint. 

Overlap is the protrusion of unfused weld metal beyond the weld toe or weld root. Overlap is a surface discontinuity that forms a mechanical notch and is nearly always considered rejectable. Two common causes of overlap may be insufficient travel speed and improper preparation of the base metal

Seams and laps are base metal discontinuities that may be found in rolled , drawn , and forged products. They differ from laminations in that they appear on the surface of the worked product . While seams and laps are surface discontinuities, they may only be detected after fabrication operations suchas bending, rolling, or sand blasting. Welding over seams and laps can cause cracking, porosity, or both

Crack

Cold cracks develop after solidification iscomplete. In carbon and low-alloy steels, cold cracks can occur in either the weld metal, heat-affected zone , or base metal , and are usually the result of dissolved hydrogen. The cracks can form hours or even days after the weldis completed. Cold cracks propagate both between grains and through grain.

Root cracks are longitudinal cracks at the weld root or in the root surface. They may be hot or cold cracks.

Excessive Reinforcement. In groove welds, weld reinforcement isweld metal in excess of the quantity required to fill a joint.Weld reinforcement can be located at either the weld face or weld root surface, and is called face reinforcement and root reinforcement, respectively

1-A visual examiner could expect to find a crater crack:

a. at the beginning of the weld

b. somewhere between the beginning and the end of the weld

c. at either the beginning or the end of the weld

d. at the end of the weld

2-During a visual examination, a welding discontinuity that could not be detected would be:

a. undercut

b. cracks

c. porosity

d. side wall lack of fusion

3-A discontinuity associated with metal overflow during forging is called a:

a. seam

b. flake

c. lap

d. lamination

4-In accordance with SNT-TC-1A certification of visual NDT personnel is the responsibility of:

a. ASNT

b. the employer

c. the NDT Level III

d. an outside agency

5-The undesirable removal of material from contacting surfaces by mechanical action is refered to as:

a. corrosion

b. erosion

c. wear

d. grinding

6-The deterioration of a metal resulting from electrochemical reactions with environment is referred to as:

a. erosion

b. corrosion

c. wear

d. fatigue

7-Welding process in which there is a higher degree of probability of entrapping slag is:

a. GMAW

b. GTAW

c. SMAW

d. all of the above

8-A cause for undercut that occurs during the welding process is called:

a. excessive voltage or current

b. slow travel speed

c. excessive travel speed

d. both a and c above

9-When the weld is to be placed on the arrow side of the joint, the weld symbol in the drawing will be:

a. below the line

b. above the line

c. in the tail

d. at the end of the arrow

10-Joint profiles of finished welds are controlled by:

a. acceptance standards.

b. workmanship standards

c. design requirements

d. all of the above