Weld Strength Calculator

by
In this Weld Strength Calculator, we will show you how to find the strength of a weld joint in just a few seconds.

We will also help you understand the meaning of weld strength,

the weld strength formula,

and how different factors like leg size, throat thickness, and weld length affect the final load capacity.

How is weld strength calculated?

Why is it so important in structures and engineering? Find all the answers right here!

Weld Strength Calculator

Enter leg size, weld length and allowable weld stress. We’ll calculate the total allowable load P = Aw × σw instantly.

Total Allowable Load (P)

—

📘 Detailed Formula Explanation

In welding design, it’s important to know how much load a weld can safely carry. The formula used is:

P = Aw × σw

  • P = Total allowable load on the weld (in lbs or N)
  • Aw = Effective throat area of the weld (in in² or mm²)
  • σw = Allowable stress or ultimate shear strength of the weld (in psi or MPa)

The effective throat area (Aw) is calculated using:

Aw = t × L

Where:

  • t = Throat thickness = w × 0.707
  • w = Leg size of the weld
  • L = Length of the weld

This formula helps engineers determine whether a weld joint is strong enough to carry the applied load without failure.

🏗️ Real-World Applications

1. Construction & Bridges

Weld strength ensures steel beams, columns, and trusses can carry the required loads safely.

2. Shipbuilding

Used to check weld joints in hulls and decks to withstand high stresses and marine loads.

3. Automotive Frames

Ensures welds on car frames and chassis can handle road vibrations and impact loads.

4. Pressure Vessels

Calculates safe weld loads in tanks and boilers subjected to high internal pressure.

🧩 Solved Example (Step-by-Step)

Problem Statement:

A fillet weld of leg size w = 6 mm and length L = 100 mm is subjected to an allowable shear stress of σw = 140 MPa. Find the total allowable load the weld can safely carry.

Step 1: Calculate the Throat Thickness

t = w × 0.707 = 6 × 0.707 = 4.242 mm

Step 2: Calculate Effective Throat Area

Aw = t × L = 4.242 × 100 = 424.2 mm²

Step 3: Find Total Allowable Load

P = Aw × σw = 424.2 × 140 = 59,388 N

✅ Final Answer:

P = 59,388 N

📋 Reference Table for Weld Strength

This table helps you understand how weld size, throat thickness, and effective throat area are related. Use it as a quick reference while calculating weld strength.

Leg Size (w)Throat Thickness (t = 0.707 × w)Weld Length (L)Effective Throat Area (Aw = t × L)Example Allowable Load (σw = 140 MPa)
3 mm2.12 mm100 mm212 mm²29,680 N
5 mm3.54 mm100 mm354 mm²49,560 N
6 mm4.24 mm100 mm424 mm²59,360 N
8 mm5.66 mm100 mm566 mm²79,240 N
10 mm7.07 mm100 mm707 mm²98,980 N

Note: The values above are for understanding only. Always use actual weld dimensions and material properties in design.

FAQs

What is weld strength?

Weld strength tells you how much load a welded part can take before it breaks. It mainly depends on the weld size, the material used, and the type of force acting on it.

Why is weld strength important?

It helps you make sure that your welds can safely carry the load without failing. From buildings to cars, almost every structure relies on strong welds to stay safe and stable.

Can this calculator be used for all weld types?

This calculator is mainly made for fillet welds, but the same concept can be used for other weld types too with just a few changes in the formula.

Leave a Comment