Link points to Internet Archive / others. Not hosted by InfraLens. Details
IS 7307:1974 Part 1 is the Indian Standard (BIS) for radiographic examination of fusion welded butt joints in steel plates - part 1: method for test. This standard (Part 1) specifies the method for radiographic examination of fusion welded butt joints in steel plates up to 50 mm thick. It details the requirements for radiographic techniques, equipment, image quality indicators (IQIs), and film processing to ensure the production of satisfactory radiographs for interpretation.
Specifies the method for radiographic examination of fusion welded butt joints in steel plates.
! This is a 'method' standard; acceptance criteria for weld defects are typically found in other codes like IS 1182 or project-specific documents.
! Proper selection between X-rays and Gamma-rays is crucial. X-rays provide better contrast on thinner sections, while portable Gamma-ray sources are often used for site work and thicker materials.
! Image Quality Indicator (IQI) placement is critical for validating the sensitivity of the radiograph. It should typically be placed on the source side.
Provides mandatory requirements and methods for radiographic examination of materials, welds, and weld overlays.
AWS D1.1/D1.1MAWS (American Welding Society), USA
MediumCurrent
Structural Welding Code — Steel
Contains a section on radiographic testing procedures and acceptance criteria specifically for structural steel welds.
BS EN ISO 17636-1:2023BSI (British Standards Institution), UK
HighCurrent
Non-destructive testing of welds. Radiographic testing - X- and gamma-ray techniques with film
The British and European adoption of ISO 17636-1, making it technically identical.
Key Differences
≠IS 7307:1974 is significantly dated and lacks the concept of 'technique classes' (e.g., Class A and Class B in ISO 17636-1) which define quality levels for the examination procedure.
≠Modern standards like ISO 17636-1 have standardized on wire-type Image Quality Indicators (IQIs) and duplex wire IQIs for measuring unsharpness. IS 7307 describes both wire-type and older step-hole type IQIs.
≠IS 7307 provides general film type descriptions ('fine grain, high contrast'), whereas modern standards classify film systems according to a specific standard (e.g., ISO 11699-1), providing a more precise and repeatable method.
≠The requirements for radiographic density in IS 7307 (1.5 to 3.5) have a lower minimum threshold compared to modern standards like ISO 17636-1 (minimum 2.0 or 2.3 depending on class), which require higher densities for better contrast sensitivity.
≠IS 7307:1974 only addresses film radiography. It contains no provisions for digital radiographic techniques (CR/DR), which are covered in separate modern standards like ISO 17636-2.
Key Similarities
≈All standards are based on the same fundamental principle of using penetrating X-rays or gamma-rays to produce an image of the internal structure of a weld on a recording medium.
≈Both IS 7307 and its international counterparts cover the use of common gamma-ray sources (Iridium-192, Cobalt-60) and X-ray equipment for the examination.
≈The use of lead intensifying screens placed on both sides of the film to reduce scatter radiation and exposure times is a recommended practice in all comparable standards.
≈All standards mandate a system of permanent identification marking on the radiograph to ensure traceability to the specific component and weld section being examined.
Parameter Comparison
Parameter
IS Value
International
Source
Image Quality Indicator (IQI) Type
Wire type (IS 1546) and Step-hole type (IS 3657) are both specified.
Primarily specifies wire type IQIs (as per ISO 19232-1).
ISO 17636-1:2022
Required Radiographic Density
Recommends a density range of 1.5 to 3.5 in the area of interest.
Requires minimum density of 2.0 for Class A and 2.3 for Class B.
ISO 17636-1:2022
Geometric Unsharpness (Ug) Limit
Recommended to be not more than the required sensitivity; no specific tabulated limits.
Specifies maximum Ug values in a table based on thickness and technique class (e.g., ≤ 0.20 mm for 20mm thickness, Class B).
ISO 17636-1:2022
IQI Sensitivity Requirement (Example)
Specifies a percentage sensitivity, e.g., 2% for plates 10-20mm thick.
Requires visibility of a specific wire number, e.g., wire W12 or W13 for 10-20mm thickness, Class B.
ISO 17636-1:2022
Minimum Source-to-Film Distance (SFD)
General recommendation of SFD > 7 times the specimen thickness.
Specifies minimum source-to-object distance (f') based on class (e.g., f' ≥ 10t for Class B), which is then used to calculate the final required SFD.
ISO 17636-1:2022
IQI Placement
On source side. For welds, placed on parent plate near and across the weld.
On source side. If not possible, on film side with a lead letter 'F' placed near the IQI.
ASME BPVC Sec V, Art 2
Hole-Type IQI Designation
Uses designation based on IS 3657.
Uses ASME/ASTM E1025 penetrameters, with designation based on material and thickness.
ASME BPVC Sec V, Art 2
⚠ Verify details from original standards before use
Key Values5
Quick Reference Values
Minimum film density (single film)1.5 H&D
Preferred film density (single film)2.0 H&D
Maximum allowable geometric unsharpness (Ug) for thickness up to 50 mm0.5 mm
Required IQI sensitivity for critical applications2% of specimen thickness
Minimum source-to-film distanceGenerally 7 times the specimen thickness
Key Formulas
Ug = f * t / D — Geometric Unsharpness (f=source size, t=thickness, D=source-to-object distance)
Tables & Referenced Sections
Key Tables
Table 1 - Recommended Wire Type Image Quality Indicators
To provide a standardized method for conducting radiographic testing on welded steel plates to ensure a consistent and reliable inspection process. (Clause 1)
What is an IQI and why is it used?+
An Image Quality Indicator (IQI) is a device used to confirm that the radiographic technique has enough sensitivity to show a small detail, ensuring the quality of the radiograph. (Clause 5)
What is the minimum recommended film density for viewing?+
The standard recommends a film density of at least 1.5, with a preference for 2.0, for proper interpretation. (Clause 6.2)
Does this standard provide acceptance limits for weld defects?+
No, this is Part 1 which only covers the 'Method for Test'. Acceptance criteria are generally covered in separate standards or project specifications.