{"id":1925,"date":"2026-06-16T17:49:28","date_gmt":"2026-06-17T00:49:28","guid":{"rendered":"https:\/\/www.songhaiflanges.com\/?p=1925"},"modified":"2026-06-21T18:18:51","modified_gmt":"2026-06-22T01:18:51","slug":"meaning-of-flanges-what-so-flange-means-slip-on-flanges-work","status":"publish","type":"post","link":"https:\/\/www.songhaiflanges.com\/de\/meaning-of-flanges-what-so-flange-means-slip-on-flanges-work\/","title":{"rendered":"Meaning of Flanges: What SO Flange Means and How Slip-On Flanges Work"},"content":{"rendered":"

Short answer:<\/strong> the meaning of flanges<\/strong> is simple: flanges are mechanical rims or collars used to connect pipes, valves, pumps, pressure vessels, instruments, filters, and equipment with bolts and a gasket. In piping, a flange creates a removable joint that can be assembled, inspected, cleaned, repaired, or replaced without cutting the pipe.<\/p>\n

One common abbreviation buyers see is SO flange<\/strong>. SO means slip-on flange<\/strong>. This flange slides over the pipe and is then welded, usually with fillet welds on both the inside and outside. It is popular because alignment is easier than with some butt-welded designs, and the manufacturing cost is often lower for standard low-to-medium service.<\/p>\n

What does flange mean in industrial piping?<\/h2>\n

In industrial piping, a flange is a bolted connection component. It usually works with another flange, a gasket, and a set of bolts and nuts. When the bolts are tightened, the gasket is compressed between the sealing faces, creating a pressure-retaining joint.<\/p>\n\n\n\n\n\n\n\n\n\n
Flange term<\/th>\nMeaning<\/th>\nWhy it matters<\/th>\n<\/tr>\n<\/thead>\n
Flange face<\/td>\nThe sealing surface that contacts the gasket<\/td>\nControls gasket compression and leakage risk<\/td>\n<\/tr>\n
Bolt circle<\/td>\nThe diameter on which bolt holes are arranged<\/td>\nMust match the mating flange<\/td>\n<\/tr>\n
Bore<\/td>\nThe internal opening through the flange<\/td>\nShould match pipe size and flow requirements<\/td>\n<\/tr>\n
Pressure class<\/td>\nA pressure-temperature rating system<\/td>\nHelps select safe flange thickness and bolting<\/td>\n<\/tr>\n
Material grade<\/td>\nThe steel or alloy used for the flange<\/td>\nDetermines strength, corrosion resistance, and weldability<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Meaning of SO flange: slip-on flange explained<\/h2>\n

The meaning of SO flange is slip-on flange<\/strong>. Its bore is slightly larger than the outside diameter of the pipe, allowing the flange to slide into position before welding. After alignment, the installer welds around the pipe at the hub side and commonly also at the inside bore side.<\/p>\n

Because the pipe enters the flange rather than being butt welded to a tapered neck, the slip-on flange is generally easier to position during installation. This makes it useful for many water, air, steam, utility, chemical, and general industrial lines where the pressure, temperature, fatigue, and corrosion conditions are within the permitted range of the piping specification.<\/p>\n

How a slip-on flange works<\/h2>\n
    \n
  1. The installer checks the pipe outside diameter, flange bore, facing, and pressure class.<\/li>\n
  2. The SO flange is slipped over the pipe end.<\/li>\n
  3. The flange is aligned with the mating flange, valve, pump, or equipment nozzle.<\/li>\n
  4. Fillet welds are applied according to the project procedure.<\/li>\n
  5. A compatible gasket is placed between the sealing faces.<\/li>\n
  6. Bolts are tightened in a controlled cross pattern to compress the gasket evenly.<\/li>\n<\/ol>\n

    Advantages of SO flanges<\/h2>\n