Stainless loose flanges, also known as lap joint flanges or loose ring flanges, are a type of flange used in piping systems where frequent dismantling or alignment adjustments are required. Here’s an overview of stainless loose flanges:

1. Design: Loose flanges consist of two main components: a stub end and a backing flange. The stub end is welded to the pipe, while the backing flange (the loose flange) slides over the stub end without being welded. The two components are then bolted together using standard flange bolts. This design allows for easy disassembly and reassembly of the piping system without disturbing the alignment of the flange faces.

2. Material: Like other stainless steel flanges, loose flanges are made from stainless steel alloys, which offer excellent corrosion resistance and durability. Common stainless steel grades used for loose flanges include 304/304L, 316/316L, and 316Ti.

3. Stub End: The stub end is welded to the pipe and typically has a lap joint or slip-on design. It serves as a connection point for the loose flange and provides a smooth sealing surface for the gasket.

4. Backing Flange: The backing flange, or loose flange, is the part that slides over the stub end. It has a flat face with bolt holes drilled around the perimeter for bolting to the mating flange or equipment. The backing flange does not have a raised face, as it does not come into contact with the gasket.

5. Assembly: To assemble a loose flange joint, the stub end is first welded to the pipe. Then, the loose flange is aligned with the stub end, and the two components are bolted together using standard flange bolts. The bolted connection provides sufficient clamping force to ensure a tight seal between the gasket and the mating flange or equipment.

6. Sizes and Ratings: Loose flanges are available in a wide range of sizes and pressure ratings to suit various piping system requirements. They can range from small diameters for residential applications to large diameters for industrial processes. Pressure ratings typically conform to standards such as ANSI/ASME B16.5 or EN 1092-1 and are expressed in classes or pressure-temperature ratings.

7. Applications: Loose flanges are commonly used in piping systems where frequent maintenance, inspection, or modifications are required. They are particularly useful in applications where equipment needs to be quickly disconnected or replaced without disturbing the rest of the piping system. Industries such as chemical processing, oil and gas, water treatment, and HVAC systems often utilize loose flanges for their versatility and ease of use.

When selecting stainless loose flanges for a piping system, it’s important to consider factors such as the application requirements, pressure and temperature conditions, material compatibility, and applicable standards to ensure proper performance and reliability. Additionally, proper installation and tightening of the flange bolts are essential to prevent leaks and ensure the integrity of the joint.