Mechanical Insulation - Insulation of Piping

Piping plays a central role in many industrial processes in chemical or petrochemical installations such as power plants, as it connects core components such as appliances, columns, vessels, boilers, turbines etc. with one another and facilitates the flow of materials and energy.

To guarantee a correct process cycle, the condition of the media within the pipes must remain within the set limitations (e.g. temperature, viscosity, pressure, etc.).

In addition to the correct isometric construction and fastening of the piping, the piping insulation also has an important function. It must ensure that heat loss are effectively reduced and that the installation continues to operate economically and functionally on a permanent basis. This is the only way to guarantee the maximum efficiency of the process cycle throughout the design service life without losses as a result of faults.

Insulation of Piping

Requirements for industrial piping

The basic efficiency and productivity factors of piping for the processing industry include: energy efficiency, dependability and reliability under different conditions, functionality of the process control, appropriate support structure suitable for the operating environment, as well as mechanical durability. The thermal insulation of piping plays a significant role in fulfilling these requirements.

Thermal insulation

The functions of proper thermal insulation for piping include:

Applicable standards - A few examples:

Minimum pipe insulation thickness

Fluid Operating Temperature Range and Usage (°F) Insulation Conductivity
Conductivity
Btu · in. /(h · ft2 · °F)b
Mean
Rating
Temperature, °F
> 350 0.32 - 0.34 250
251 - 350 0.29 - 0.32 200
201 - 250 0.27 - 0.30 150
141 - 200 0.25 - 0.29 125
105 - 140 0.21 - 0.28 100
40 - 60 0.21 - 0.27 75
< 40 0.20 - 0.26 75
Nominal Pipe or Tube Size (inches)
< 1 1 to < 1-1/2 1-1/2 to < 4 4 to < 8 ≥ 8
4.5 5.0 5.0 5.0 5.0
3.0 4.0 4.5 4.5 4.5
2.5 2.5 2.5 3.0 3.0
1.5 1.5 2.0 2.0 2.0
1.0 1.0 1.5 1.5 1.5
0.5 0.5 1.0 1.0 1.0
0.5 1.0 1.0 1.0 1.5

a For piping smaller than 1-1/2 inch (38 mm) and located in partitions within conditioned spaces, reduction of these thicknesses by 1 inch (25 mm) shall be permitted (before thickness adjustment required in footnote b) but not to a thickness less than 1 inch (25 mm).

b For insulation outside the stated conductivity range, the minimum thickness (T) shall be determined as follows:

T = r{(1+t/r) K/k-1}

Where:

T = Minimum insulation thickness
r = Actual outside radius of pipe
t = Insulation thickness listed in the table for applicable fluid temperature and pipe size
K = Conductivity of alternate material at mean rating temperature indicated for the applicable fluid temperature (Btu x in/h x ft2 x °F) and
k = The upper value of the conductivity range listed in the table for the applicable fluid temperature

c For direct-buried heating and hot water system piping, reduction of these thicknesses by 1-1/2 inches (38 mm) shall be permitted (before thickness adjustment required in footnote b but not to thicknesses less than 1 inch (25 mm).

Insulation of piping
1. Pipe   2. Insulation   3. Clamp or binding wire   4. Sheet cladding
5. Sheet-metal screw or rivet

Cladding

Suitable cladding should be applied to protect the insulation from weather influences, mechanical loads and (potentially corrosive) pollution. Selecting the appropriate cladding depens on various factors, such as working loads, wind loads, ambient temperatures and conditions.

When selecting the appropriate cladding, take the following points into account:

Reference(s):
https://www.wbdg.org, http://www.roxul.com, http://apps.leg.wa.gov/wac

More about Mechanical Insulation

Part 1:
Mechanical Insulation - Types and Materials

Part 2:
Mechanical Insulation - Space Requirements of Insulation

Part 3:
Mechanical Insulation - Insulation of Piping

 

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