Slip-On Flange

A slip-on flange is a flat, ring-shaped flange designed to slide over the outside diameter of a pipe end. Once positioned, it is secured with two fillet welds — one on the inside bore and one on the outside face — creating a strong, leak-resistant joint. This double-weld configuration provides adequate strength for the majority of general service applications while keeping fabrication straightforward and cost-effective.

Key Advantages

Slip-on flanges offer two primary advantages over weld-neck flanges: ease of alignment and lower cost. Because the pipe simply slides through the bore, precise pipe-end preparation is less critical, reducing fit-up time on site. The flanges themselves are less expensive to manufacture, making them the preferred choice wherever pressure and fatigue requirements do not demand the superior strength of a weld-neck design.

Materials

Slip-on flanges are available in a range of materials to suit different service conditions. Carbon steel grade A105 is the standard choice for general-purpose and high-temperature applications. Stainless steel grades 304 and 316 are specified where corrosion resistance is required, such as in chemical processing, food-grade, or marine environments.

Size Range & Pressure Classes

Available in nominal pipe sizes from 1/2" through 64", slip-on flanges cover the full spectrum of industrial piping requirements. Pressure ratings span ANSI Class 150 through Class 600 per ASME B16.5, and PN10 through PN40 under the DIN standard, accommodating a wide range of operating pressures.

Face Types

Two standard face types are offered. Raised Face (RF) flanges feature a small raised seating area that concentrates gasket load and is the most common choice for ANSI-class systems. Flat Face (FF) flanges present a flush mating surface and are typically used when connecting to cast-iron or non-metallic equipment to avoid bending stresses.

Applicable Standards

Slip-on flanges are manufactured in accordance with ANSI/ASME B16.5 for inch-dimensioned piping systems and DIN 2576 for metric piping systems, ensuring dimensional interchangeability and compliance with international procurement specifications.

Typical Applications

Due to their versatility and economy, slip-on flanges are widely used across industries including general service piping, water treatment and distribution, oil and gas gathering systems, and chemical processing plants. They are particularly well-suited to low- and medium-pressure systems where ease of installation and cost efficiency are priorities.