Radiographic Test (X-Ray and Gamma)

Radiographic Test (X-Ray and Gamma)

Equipment Needs:

X-ray sources, Gamma ray sources, gamma ray camera protectors, film holders, lead screens, film processing equipment, film viewers, exposure facilities, radiation monitoring equipment.

Applications:

Welds which have voluminous discontinuities such as porosity, incomplete joint penetration, corrosion, etc. Lamellar type discontinuities such as cracks and incomplete fusion can be detected with a lesser degree of reliability. May also be used in certain applications to evaluate dimensional requirements such as fit-up, root conditions, and wall thickness.

Advantages (X-ray):

Adjustable energy levels. Generally produces higher quality radiographs than gamma sources. Surface and subsurface inspection capability. Radiographic images aid in characterizing discontinuities. Provides a permanent record for future review.

Advantages (Gamma):

Generally not restricted by type of material or grain structure. Surface and subsurface inspection capability. Radiographic images aid in characterizing discontinuities. Provides a permanent record for future review.

Limitations:

Planar discontinuities must be favourably aligned with radiation beam to be reliably detected. Radiation poses a potential hazard to personnel. Cost of radiographic equipment, facilities, safety programs and related licensing is relatively high. A relatively long time between exposure process and availability of results. Accessibility to both sides of the weld required. High initial cost of X-ray equipment. Not generally considered portable.

 

Sample Questions for Radiographic Testing – General

Sample Questions for Radiographic Testing – Specific

 

Source: American Welding Society Inc., The McGraw-Hill Companies Inc.