The following are some formula for calculating the area of additional shapes we’ll use
to define weld
volume in a joint:

For the Triangle on the right: Area = B_{ * }H / 2

Note it is
like calculating the **Area** of a **Rectangle** and dividing by
**2**.

This
formula works for
any size and shape **Triangle. ** Look at the **Triangle** below
left. Below right are picture examples that help show why this
equation works for any shape **Triangle**:

By
duplicating the **Blue Triangle **and rearranging pieces ** **we can construct a
rectangle:

Referring to the three pictures on the
right:

1) In the
top picture the **Blue Triangle is copied **and turned upside down
It is shown in **Green.**

2) In the
middle
picture we make a small **Red Triangle** to create a straight
perpendicular side on the **Blue Triangle**.

3) In the
bottom picture the **Red Triangle **is moved to the left side making a
straight side on the **Green Triangle**.

4) That makes a **Rectangle** with one
side still equal to** B **and the other **H**.

5) The **AREA **as defined for a **
Rectangle** is **B**_{ *}** H**.
But remember we duplicated the **Blue Triangle** so to get the **AREA
**of the **Original Blue Triangle** we have to divide by **2** hence
the** **formula**: Area = B **_{*}** H / 2**

Area of a
Segment (Weld Reinforcement)

This
is one **Area** that is
often used in calculating weld metal area and
volume; it is called the area of a **Circle Segment** and shown in **Red**
on the photo left. This is what is used to calculate the area of **
Weld Reinforcement**. The accurate way to do this is to calculate the area of a
segment of **Radius R (that is the combined Green and Red Areas**;) use
the length of the **Cord W **(width of weld) and subtract the area of the
triangle formed by the **Cord **and **distance **from the** Center of
the Circle** and the **Cord (the Green Area.) **This leaves the **Area **between the**
Cord** and the **Outer Area of the Circle** **(Red Area)** or **Weld Reinforcement **
in our case.

However we
would have to estimate the **Radius **of the circle making the
reinforcement and the angle of that **Segment**. Not an easy item to
estimate. Since we know the weld bead height (or the desired maximum height
by code, usually 3/32 or 1/8 inch) and the weld height is much smaller than
the weld width we can use a method that estimates the area and is
probably
better than estimating the radius. The formula is:

Approximate** Area of a Segment (Weld Reinforcement) = (2 H**_{ *}** W)**_{ }**/ 3 + H**^{ 2 }/ 2W

Since weld reinforcement is not a
perfect circle, the value obtained is sufficiently accurate for any
engineering calculations needed. In fact since weld reinforcement is
not a portion of a perfect circle this approach may be closer to the actual
area/volume!
** Having checked several typical weld reinforcements dimensions you
can use 72% of the Area of a Rectangle for the estimate of
reinforcement.**

**With
these basic shapes you can calculate the area of almost all welds. **

Look at
the following examples of the of weld joints; the weld area can be arranged
into **Triangles**, **Rectangles and Segments.**

To
calculate the weld metal volume that must be added to a weld joint you simply multiply the
**Area** times the **Length** in
the same dimensions. Therefore if the length is given in feet convert it to
inches so all dimensions
are in inches. Therefore **Area in**^{2} * Length in = Volume in^{3}.
Remember dimensional analysis
works to check your work** in**^{ 2} * in = in^{3}.

Calculate Pounds of Welding Materials Needed:

Now the **Volume** of weld metal you’ll
need to add is known , how much wire will you
need? The following are some material densities:

**Steel
weights: 0.284 lb / in**^{3}; **Aluminum = 0.098 lb / in**^{3}
depending
somewhat on alloy and **Stainless Steel 0.29 lb / in**^{3} again
depending on the alloy.