WHAT IS THE MINIMUM DISTANCE BETWEEN WELDS

WHAT IS THE MINIMUM DISTANCE BETWEEN WELDS🤔

👉The minimum distance between welds depends on the type of weld, the materials being joined, the applicable code or standard, and the service conditions (e.g., pressure, temperature, fatigue). However, here’s a general guideline:

🔧 General Rule of Thumb

For butt welds on piping and pressure vessels:

Minimum distance between adjacent circumferential welds (center to center):

🔹 1.5 × the pipe wall thickness, or

🔹 Not less than 25 mm (1 inch)

Whichever is greater

🛠️ Applicable Standards

Here’s what some codes say:

1. ASME B31.3 (Process Piping)

 • Paragraph 328.5.4:

Welds on adjacent piping joints should be separated by at least one pipe diameter, but not less than 25 mm, unless a closer spacing is justified.

2. ASME Section VIII (Pressure Vessels)

 • For pressure parts, weld spacing should ensure no overlap of heat-affected zones (HAZ).

 • If welds are too close, stress concentration and metallurgical issues may arise.

3. API 650 (Storage Tanks)

 • For shell courses, minimum distance is 100 mm (4 inches) between horizontal and vertical welds.

❗Why Spacing Matters:

 • Prevents overlapping HAZ that weakens the material.

 • Allows proper NDT (Non-Destructive Testing) access.

 • Avoids residual stress accumulation and cracking.

📌 In Summary:

Condition               Minimum Weld Spacing

General piping      1.5× wall thickness or 25 mm

Per ASME B31.3    ≥ 1× pipe diameter or ≥ 25 mm

API 650 (Tank).     ≥ 100 mm (4 inch)

If unavoidable        Engineering review & stress 

                                 analysis may be required