Why do we straddle bolt holes in flanges?
Purpose The purpose of this check is to ensure that the flange hole shape can be manufactured using standard pierce equipment.
What does one hole a flange mean?
To “One-Hole” a flange means that the flange has been rotated so that one hole is right on the natural centerline.
What is a flange bolt?
Flange bolts have a circular flange under the head that acts like a washer to distribute the load. Flange bolts that are non-serrated are sometimes called frame bolts.
How many bolt holes in a flange?
Generally, higher pressure class flanges will have more bolt holes and/or larger bolt hole diameters. A 2″ Class 150# flange has 4 holes and a 2″ Class 300# flange has 8 bolt holes.
How do you check flange orientation?
Position, or check, vertical orientation of both end flanges using the carpenter’s level, as illustrated. Using two equal diameter pins located in two adjacent bolt holes, orient the flange on one end so that the carpenter’s level resting on the pins indicates level.
How many types of flanges are there?
The key types of flanges are the welding neck, long welding neck, slip-on, socket weld, lap joint, threaded and blind flanges. In addition to these standard flanges, some special ones exist, called Weldoflange/Nipoflange and Elboflange, swivel flange, expander/reducer flange, and orifice flanges.
How do flange bolts work?
A flange bolt differs from the common bolt in that it has a wider surface area under the head to provide for an even distribution of clamping pressure. This wider surface acts like a washer, eliminating the need to combine one with this kind of bolt.
What is a flange used for?
Flanges are helpful to connect pumps, valves, pipes, and other parts to form a piping system. Flanges are typically welded or thread screwed to connect. The use of flanges allows a person for maintenance and easy repair of the pipe system.
How do I choose bolts for flange?
The quantity of bolts for a flange connection will be given by the number of bolt holes in a flange, diameter and length of bolts is dependent of flange type and Pressure Class of flange. Stud Bolt length are defined in ASME B16. 5 standard.
How many bolt holes in a 10 flange?
Diameters and bolt circles for standard ASME B16. 5 flanges – 1/4 to 24 inches – Class 150 to 2500.
| Nominal Pipe Size NPS (inches) | Class 400 | |
|---|---|---|
| Diameter of Flange (inches) | Diameter of Bolt Holes (inches) | |
| 6 | 12-1/2 | 1 |
| 8 | 15 | 1.12 |
| 10 | 17-1/2 | 1.25 |
What are the two main types of flanges?
We usually consider two main families of flanges, the standard flanges and the special ones.
Why do bolt holes on flanges straddle center lines?
Here’s a copy/paste from Yahoo answers, of all places. Looks right to me. “Bolt holes on flanges straddle the center lines (one on each side of the center line) for a very simple reason, To assure proper alignment of flanges from piece to piece there needs to be a simple method of consistently orienting the bolt holes.
What is the two hole rule for flange bolts?
Re: Two Hole Rule For Flange. For example- on a 4 bolt flange with 1/8″ clearance for the bolts, if one bolt is at the top of the hole and the adjacent one is at the bottom, the flange bolts will not be inline. Do this with both ends of the pipe and it possibly doubles the error.
How do you orientate bolt holes on flanges?
“Bolt holes on flanges straddle the center lines (one on each side of the center line) for a very simple reason, To assure proper alignment of flanges from piece to piece there needs to be a simple method of consistently orienting the bolt holes. By using a simple spirit level it is possible to set the hole orientation.
What happens if a bolt is at the bottom of flange?
If a bolt is at the bottom of the flange it will experience accelerated corrosion, failure and lead to a major leak. Biggy’s answer sounds reasonable but I’m guessing it also has to do with standard convention.