hnf posted an update 1 week, 5 days ago
Tees straight and reducing
Standard there are 2 possibilities, on behalf of the equal tee and reducing tee. The equal tee (or straight tee) is used as the branch has the same diameter as the run-pipe. The reducing tee is used as the branch has a smaller diameter as the run-pipe.
Dimensions and Standards
When we talk about a tee NPS 3, a equal or straight tee is intended. With a tee NPS 3 x 2 a reducing tee is intended. Although, officially a reducing tee will be indicated by 3 diameters, namely 3 x 3 x 2 (A x B x C). The A & B measure stands for the Nominal Pipe Size of Run-Pipe, C measure stands for Nominal Pipe Size of Outlet.
This designation actually is superfluous, but comes from the time that tees were available in 3 different ends of diameters, such as
4 x 3 x 2 (A x B x C). In this implementation of course it is necessary, to specify 3 different sizes.
That kind of tees is probably no longer available. Applying a equal tee with a concentric or eccentric reducer is now the usual practice.
A straight or equal buttwelding Tee is available for all common diameters.
A Reducing Tee not, because many diameters are not produced, or can not be produced.
As an example: a reducing tee NPS 6 x 4 is a standard item for most suppliers, but a reducing tee NPS 16 x 2 is probably not available by any supplier.
It would also not economical to use a NPS 16 tee with a NPS 2 outlet; in such situations a Branch Fitting will be used or a Branch Connection will be made.
In addition to the defined tees, there are straight and reducing crosses.
Straight crosses are generally stock items, reducing crosses are often difficult to obtain.
I have never used that tees and I have they never seen in practice, at least not in petro and chemical industry. They will be used where space is limited, by revision work, in shipping industry et cetera.
Wall thickness Tee
By the shape of a tee, the wall thickness can be a critical item. ASME B16.9 only standardizes the end-to-end dimensions, center-to-end dimensions and some “squareness” dimensional tolerances.
The wall thickness at the weld line location even is standardized, but not through the rest of the fitting. The standard states that the minimum tolerance will be within 12.5% of the minimum ordered wall thickness of the pipe. A maximum tolerance is specified only at the ends of the fitting.
Many providers of welding tees (and elbows) provide one schedule greater thickness so that sufficient wall thickness, after forming, remains. In Tee’s, the crotch radius (T) varies from one manufacturer to another, but some establish itself as a requirement, 1.3 times the wall thickness to maintain the crotch.
Crotch of a buttweld tee
ASME B16.9-2003 Section 2.2 Design of fittings says:
…it is expected that some portion of formed fittings may have to be thicker than the pipe wall with which the fitting is intended to be used
Because there is no maximum tolerance for some parts of the fitting, the customer itself must indicate his requirements. Depending on a customer specification, the manufacturer must certify that the manufactured tee, is made the requested requirements.
He can do that with additional drawings, with additional wall thickness measurements etc. verified by an independent party or a customers inspector.
All these additional tests cost money, so it can happen, that the additional costs, many times higher, as the tee itself.
Common types of pipe tee
A pipe tee is a type of fitting that has a T shape and is used to join two or more plumbing pipes.
· Equre tee (or straight tee), means the branch diameter of this tee is same with the main pipe (Run pipe) diameter of this tee.
· Reducing tee is a type of pipe fitting in which the branch port size is smaller than the ports of the run.
· Barred tee is used in pipelines that are pigged.
· Lateral tee has a 45 degree branch from a pipeline.
· Pipe cross is a fitting that used in the place where four pipes meet with the same diameter include:
o Reducing cross used for connecting four pipes, the main pipes with the same size, but the dimensions of the branch diameter is smaller than the main pipes.
o Equal cross in the place where four pipes meet with the same diameter.
· Forged Tee Fittings are pipe fittings that be formed mainly by forging.
Carbon steel: ASTM/ASME A234 WPB-WPC
Alloy steel: ASTM/ASME A234 WP 1-WP 12-WP 11-WP 22-WP 5-WP 91-WP 911
Stainless steel: ASTM/ASME A403 WP 304-304L-304H-304LN-304N
ASTM/ASME A403 WP 316-316L-316H-316LN-316N-316Ti
ASTM/ASME A403 WP 321-321H ASTM/ASME A403 WP 347-347H
Low temperature steel: ASTM/ASME A402 WPL 3-WPL 6
High performance steel: ASTM/ASME A860 WPHY 42-46-52-60-65-70
Size range: 1/2 to 72 inches
Pressure: SCH5 to SCH160
Welding Bevel acc. to standards:
· ASME B16.9, Factory-Made Wrought Steel Buttwelding Fittings
· ASME B16.28, Buttwelding Short Radius Elbows and Returns
· ANSI/ASME B16.25, Buttwelding Ends
· MSS SP-97, Socket Welding, Threaded, and Buttwelding Ends
· Tolerance For butt Welding Fittings
Industrial Processes : Bending, squeezing, pressing, forging, machining and more
Features of Pipe Tee:
· There are three female openings in a T shaped pipe tee.
· There are straight pipe tees which have the same size openings.
· Reducing pipe tees have one opening of different size and two openings of the same size.
· There are sanitary pipe tees which are used in waste lines. These kind of pipe tees have a curved branch which is designed for a clean out plug. They are used to prevent obstruction of waste.
· A cross pipe tee has four equal sized female openings.
· A wing pipe tee has lugs to fasten the fitting to a wall or stud.
· A compression pipe tee uses compression fittings on two or more ends.
· A test pipe tee has a threaded opening. This opening is used in conjunction with a threaded plug for a clean-out opening on a drain pipe.
Related products of pipe tee:
· Saddle previously is the ventilation ducts ‘crotch tee’, its shaped like pants, there Equal and unequal diameter, the formal name is “tube tapered pants tee.”
o Saddle previously DIN2618 is to replace the existing tee fitting, the use of flexibility, praised by domestic and foreign markets.
· Stainless steel Tee is T-shaped pipe fittings with two outlets, one at 90° to the connection to the main line by stainless.
· Tees straight and reducing- The primary purpose of a Tee is to make a 90° branch from the main run of pipe.
· Wear-resistant Alloy Composite Pipe Tee
· Ceramic lined composite Y-type Tee
· Ceramic lined composite pipe tee
· Aluminum corundum lined lateral wye
· Bi-metal clad lateral wye
Applications of pipe tee:
Pipe Tees are widely used in various commercial and industrial applications. Industrial applications include:
· Chemical processing
· Waste treatment, Marine
· Utilities/power generation
· Industrial equipment
· Gas compression and distribution industries
· Pipe Tees are also recommended for industrial plant fluid power systems.
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