The following QUALITY REQUIREMENTS for the various insulating materials are taken into consideration by the Navy in the standardization of these materials:

1. Low heat conductivity

2. Noncombustibility

3. Lightweight

4. Easy molding and installation capability

5. Moisture repellant

6. Noncorrosive, insoluble, and chemically inactive

7. Composition, structure, and insulating properties unchanged by temperatures at which it is to be used

8. Once installed, should not cluster, become lumpy, disintegrate, or build up in masses from vibration

9. Verminproof

10. Hygienically safe to handle

Insulating material is available in preformed pipe coverings, blocks, batts, blankets, and felts. Refer to NSTM, Chapter 635, "Thermal, Fire, and Acoustic Insulation," for detailed information on insulating materials, their application, and safety precautions.

The insulating cements are comprised of a variety of materials, differing widely among themselves as to heat conductivity, weight, and other physical characteristics. Typical of these variations are the asbestos substitute cements, diatomaceous cements, and mineral and slag wool cements. These cements are less efficient than other high-temperature insulating materials, but they are valuable for patchwork emergency repairs and for covering small irregular surfaces (valves, flanges, joints, and so forth). Additionally, the cements are used for a surface finish over block or sheet forms of insulation, to seal joints between the blocks, and to provide a smooth finish over which asbestos substitute or glass cloth lagging may be applied.

REMOVABLE INSULATION

Removable insulation will be found on the bleed air systems and waste heat boiler systems. Removable insulation is also installed in the following locations:

Flange pipe joints adjacent to machinery or equipment that must be broken when units are opened for inspection or overhaul

Valve bonnets of valves larger than 2 inches internal pipe size (IPS) that operate at 300 psi and above or at 240F and above

All pressure-reducing and pressure-regulating valves, pump pressure governors, and strainer bonnets