RF = Raised Face

For Valves with Flanges, 2 popular facings are:
a) Raised Face, commonly known as RF;
b) Ring Joint, commonly known as RTJ, Ring To Joint.

There are 2 type of RF:
a) 2 mm Raised Face,
b) 7 mm Raised Face.

2 mm Raised Face is used on flanges of  valves with pressure rating of 150LB and 300LB.

7 mm Raised Face is used on flanges of  valvs with pressure rating of 400LB, 600LB, 900LB, 1500LB and 2500LB.

For RTJ flanges, it is important to know the Groove Number (also known as R Number, or Ring Number).  So we know what-size Ring to use for the RTJ groove.

A good standard to read about RF flange dimensions and RTJ flange dimensions is ASME B16.5 - Pipe Flanges and Flange Fittings.

ASME Class 600 and 900 Valves –Gate, Globe, Check, Ball

Table 3 shows the Face-to-Face and End-to-End dimensions of ASME class 600LB valves.  Table 4 shows the ASME class 900LB valves.  Valve types listed in Table 5 of ASME B16.10 are Gate Valves, Plug Valves, Globe Valves, Lift Check Valves, Swing Check Valves, Angle Valves, and Ball Valves.

For ASME class 600, long-pattern Gate Valves, size range is NPS ½ ” up to NPS 36”, connections are flanges and welding ends.  For class 600 short-pattern Gate Valves, size range is NPS 1” up to NPS 24”, connection is welding ends. For size of NPS 1” up to NPS 12”, there is obvious dimensional difference between long-pattern and short-pattern valves.

For ASME class 900, long-pattern Gate Valves, size range is NPS 1” up to NPS 24”, connections are flanges and welding ends.  For class 900 short-pattern Gate Valves, size range is NPS 1” up to NPS 16”, connection is welding ends.  There is obvious dimensional difference between long-pattern and short-pattern valves, for size of NPS 1” up to NPS 16”.

For ASME class 600, long-pattern Globe Valves, size range is NPS ½ ” up to NPS 36”, connections are flanges and welding ends.  For class 600 short-pattern Globe Valves, size range is NPS 1” up to NPS 12”, connection is welding ends.  For size range of NPS 1” up to NPS 12”, there is obvious dimensional difference between long-pattern and short-pattern valves.

For ASME class 900, long-pattern Globe Valves, size range is NPS  ¾ ” up to NPS 24”, connections are flanges and welding ends.  For class 900 short-pattern Globe Valves, size range is NPS 2 ½ ” up to NPS 16”, connection is welding ends.  For size range of NPS 2 ½ ” up to NPS 16”, there is obvious dimensional difference between long-pattern and short-pattern valves.

For ASME class 600, long-pattern Globe Valves, size range is NPS ½ ” up to NPS 36”, connections are flanges and welding ends.  For class 600 short-pattern Globe Valves, size range is NPS 1” up to NPS 12”, connection is welding ends.  For size range of NPS 1” up to NPS 12”, there is obvious dimensional difference between long-pattern and short-pattern valves.

For ASME class 900, long-pattern Swing Check Valves, size range is NPS  ¾ ” up to NPS 24”, connections are flanges and welding ends.  For class 900 short-pattern Swing Check Valves, size range is NPS 2 ½ ” up to NPS 16”, connection is welding ends.  For size range of NPS 2 ½ ” up to NPS 16”, there is obvious dimensional difference between long-pattern and short-pattern valves.

For ASME class 600, long-pattern Lift Check Valves, size range is NPS ½ ” up to NPS 36”, connections are flanges and welding ends.  For class 600 short-pattern Globe Valves, size range is NPS 1” up to NPS 12”, connection is welding ends.  For size range of NPS 1” up to NPS 12”, there is obvious dimensional difference between long-pattern and short-pattern valves.  Lift Check Valve is also known as Piston Check Valve.

For ASME class 900, long-pattern Lift Check Valves, size range is NPS  ¾ ” up to NPS 24”, connections are flanges and welding ends.  For class 900 short-pattern Lift Check Valves, size range is NPS 2 ½ ” up to NPS 16”, connection is welding ends.  For size range of NPS 2 ½ ” up to NPS 16”, there is obvious dimensional difference between long-pattern and short-pattern valves. Lift Check Valve is also known as Piston Check Valve.

For ASME class 600, long-pattern Ball Valves, size range is NPS 1” up to NPS 24”, connections are flanges and welding ends.  There is no short-pattern specified for Ball Valves. 

For ASME class 900, long-pattern Ball Valves, size range is NPS 1” up to NPS 24”, connections are flanges and welding ends.  There is no short-pattern specified for Ball Valves. 


Reference:
ASME B16.10  -  Face-to-Face and End-to-End Dimensions of Valves.
Table 3  –  Class 600 Steel Flanged and Buttwelding End Valves, Face-to-Face and End-to-End Dimensions.
Table 4  –  Class 900 Steel Flanged and Buttwelding End Valves, Face-to-Face and End-to-End Dimensions.

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ASME Class 1500 Valves – Ball, Gate, Globe, Check

Table 5 shows the Face-to-Face and End-to-End dimensions of ASME class 1500LB valves.  Valve types listed in Table 5 of ASME B16.10 are Gate Valves, Plug Valves, Globe Valves, Lift Check Valves, Swing Check Valves, Angle Valves, and Ball Valves.

For long-pattern Ball Valves, size range is NPS 2” up to NPS 16”, connections are flanges and welding ends.  There is no short-pattern specified for Ball Valves. 

For long-pattern Gate Valves, size range is NPS 1” up to NPS 24”, connections are flanges and welding ends.  For short-pattern Gate Valves, size range is NPS 1” up to NPS 20”, connection is welding ends.

For long-pattern Globe Valves, size range is NPS ½” up to NPS 24”, connections are flanges and welding ends.  For short-pattern Globe Valves, size range is NPS 2” up to NPS 16”, connection is welding ends.  For size range of NPS 2” up to NPS 16”, there is obvious dimensional difference between long-pattern and short-pattern valves.

For long-pattern Swing Check Valves, size range is NPS ½” up to NPS 24”, connections are flanges and welding ends.  For short-pattern Swing Check Valves, size range is NPS 2” up to NPS 16”, connection is welding ends.  For size range of NPS 2” up to NPS 16”, there is obvious dimensional difference between long-pattern and short-pattern valves.

For long-pattern Lift Check Valves, size range is NPS ½” up to NPS 24”, connections are flanges and welding ends.  For short-pattern Lift Check Valves, size range is NPS 2” up to NPS 16”, connection is welding ends.  For size range of NPS 2” up to NPS 16”, there is obvious dimensional difference between long-pattern and short-pattern valves.  Lift Check Valve is also known as Piston Check Valve.

Reference:
ASME B16.10  -  Face-to-Face and End-to-End Dimensions of Valves.
Table 5  –  Class 1500 Steel Flanged and Buttwelding End Valves, Face-to-Face and End-to-End Dimensions.

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ASME Class 2500 Valves – Gate, Globe, Check, Ball

Valve types listed in Table 6 of ASME B16.10 are Gate Valves, Plug Valves, Globe Valves, Lift Check Valves, Swing Check Valves, Angle Valves, and Ball Valves.

For long-pattern Gate Valves, size range is NPS ½” up to NPS 12”, connections are flanges and welding ends.  For short-pattern Gate Valves, size range is NPS 1” up to NPS 18”, connection is welding ends.

For long-pattern Globe Valves, size range is NPS ½” up to NPS 12”, connections are flanges and welding ends.  For short-pattern Globe Valves, size range is NPS 2” up to NPS 12”, connection is welding ends.  For size range of NPS 2” up to NPS 8”, face-to-face and end-to-end dimensions for Long Pattern and end-to-end dimensions for Short Pattern are similar.  In other words, the differential longer and shorter Gate Valves are applicable only for size NPS 10” and NPS 12”.

For long-pattern Swing Check Valves, size range is NPS ½” up to NPS 12”, connections are flanges and welding ends.  For short-pattern Swing Check Valves, size range is NPS 2” up to NPS 12”, connection is welding ends.  For size range of NPS 2” up to NPS 8”, face-to-face and end-to-end dimensions for Long Pattern and end-to-end dimensions for Short Pattern are similar.  In other words, the differential longer and shorter Swing Check Valves are applicable only for size NPS 10” and NPS 12”.

For long-pattern Lift Check Valves, size range is NPS ½” up to NPS 12”, connections are flanges and welding ends.  For short-pattern Lift Check Valves, size range is NPS 2” up to NPS 12”, connection is welding ends.  For size range of NPS 2” up to NPS 8”, face-to-face and end-to-end dimensions for Long Pattern and end-to-end dimensions for Short Pattern are similar.  In other words, the differential longer and shorter Lift Check Valves are applicable only for size NPS 10” and NPS 12”.  Lift Check Valve is also known as Piston Check Valve.

For long-pattern Ball Valves, size range is NPS 2” up to NPS 12”, connections are flanges and welding ends.  There is no short-pattern specified for Ball Valves. 

Reference:
ASME B16.10  -  Face-to-Face and End-to-End Dimensions of Valves.
Table 6  –  Class 2500 Steel Flanged and Buttwelding End Valves, Face-to-Face and End-to-End Dimensions.


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POVE Valves - Ball, Gate, Globe, Check, DBB: POVE brand Small Forged Ball Valves

POVE Valves - Ball, Gate, Globe, Check, DBB: POVE brand Small Forged Ball Valves

Difference between API 6D and API 6A Valves

API 6D and API 6A are both standards used for Valves in the oil and gas industry.  What is the difference?  Why is API 6D more popular?

API 6D is standard or specification for valves in any pipeline, including rigs, platforms, skids and production plants.  API 6A is standard or specification for valves used in wellhead and Christmas tree equipment.

In terms of usage, there are many more pipeline valves used as compared to wellhead valves. 

In terms of ease of manufacture, pipeline valves are more easily manufactured as compared to wellhead valves.

In terms of pressure rating, the most common rating for API 6D valves are from 150LB to 2500LB, i.e. 150LB, 300LB, 600LB, 800LB, 900LB, 1500LB, and 2500LB.  API 6A valves are pressure rated for 2000LB up to 20000LB, i.e. 2000LB, 3000LB, 5000LB, 10000LB, 15000LB, and 20000LB.

Generally, the pressure rating for API 6A valves are higher than API 6D valves.


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API Standards for Valves

There are several API standards concerning valves.

API is abbreviation for American Petroleum Institute.

API 598 Valve Inspection & Testing
API 598 details all the testing and inspection requirements for gate, globe, plug, ball, check and butterfly valves. ASME/ANSI B16.34 determine the test pressures required for API 598.  For steel valves, ASME B16.34 need to be used in conjunction with API 598.

API 6D Specification for Pipeline Valves (Plug, Gate, Ball and Check Valves)
API 6D is the standard used for valves in pipeline service. API 6D has more stringent testing requirements compared to the API 600, 602, 608 or 609 design criteria. API 6D check valves are used in applications requiring pigging as the spec indicates the flapped cannot impede flow through the valve.
API 6D is the most popular standard used for valves for petrochemical, oil and gas industry.

API 600 - Steel Valves - Flanged & Buttwelding Ends
API 600 is the primary steel gate valve specification. API 600 details valve design/construction criteria as well as material/trim designations. ISO 10434 is a similar spec published in the ISO format.

API 602 - Compact Steel Gate Valves-Flanged, Threaded, Welding and Extended-Body Ends
API 602 is for 4" and smaller forged steel gate valves. Like API 600 the spec details valve design/construction criteria as well as material/trim designations.

API 603 - Corrosion-Resistant, Bolted Bonnet Gate Valves – Flanged and Butt-Welding Ends
API 603 is the specification for light-walled threaded gate valves ranging through ½" to 24" in ANSI 150, 300 and 600. API 603 is for thin walled applications where the thicker API 600 is not required.

API 607 (API 6FA) -API 607 is a fire test for soft-seated quarter turn valves; the standard covers testing and performance requirements for valves exposed to certain fire conditions defined in the standard. The procedures defined in this standard apply to all valves made from materials listed in ASMB B16.34. API 6FA is the fire test spec for API Spec 6A and 6D valves; API 6FC is the fire test for valves with automatic backseatsAPI Spec 6A and 6D valves.

API 608 - Metal Ball Valves- Flanged and Butt-Welding Ends
API 608 is the specification for class 150 and 300 metal ball valves. Design and construction criteria are detailed in this spec.

API 609 - Butterfly Valves, Lug-Type and Wafer Type
API 609 is the purchase specification for lug and wafer type butterfly valves for installation between ANSE B16 flanges up to Class 600

Ball Valves: importance of the Ball

Some are surprised over the price variation of the Ball Valve.  Yes, Ball Valve can vary much dependent on several factors such as:
1)  Body type – forged or cast.  3-piece design of forged steel body is generally more expensive.
2)  Ball material.  For carbon steel and stainless steel ball valves, the ball is usually stainless steel for reason of corrosion protection and long-term leakage prevention.  Stainless steel 316 ball is indeed more expensive than stainless steel 304 ball.
3)  Ball type.  There are 3 types:  solid forged steel ball, solid cast steel ball, and hollow welded steel ball.  Solid forged steel ball is the most expensive whereas hollow welded steel ball is the cheapest.
4)  Ball plating and coating.  Ball could be plated with chrome or electroless nickel.  Ball could be coated with Stellite, chrome carbide, tungsten carbide or Teflon.  Non-plated, non-coated ball is the cheapest option.
5)  Facility grade.  What is the grade of factory and machinery used for making the balls and ball valves?  Grade A factory has CNC spherical grinders and 5-axis CNC lathe equipped with rotating table to manufacture the balls.  Valve seats are also machined using CNC lathe and CNC vertical machining centre.  On the opposite end, Grade C factory uses manual machining method whereby accuracy and precision is not guaranteed.
6)  Full-bore or Reduced-bore.  Full-bore ball valve is always more expensive, larger and heavier than the reduced-bore ball valve.

Ball valve is the most important of all mechanical valves (ball valves, gate valves, globe valves, gate valves, check valves, butterfly valves, etc.).  Ball valve is often used as a control valve in the pipeline.  So, don’t be a cheapskate.  Do buy Grade A ball valves.  Yes, Grade A ball valves are much more expensive than Grade B ball valves, but ball valves are crucial and daily used.  Ball valves need to be the best in quality, reliability and durability. 
Forget the Grade C ball valves, unless you intend to be a Cheat, a hit-and-run businessman.

In this blog post, let us look at the Quality aspect of the Ball.

Solid forged steel ball is the best option.  Steel is forged out of a solid, round steel bar.  The solid forged steel ball is denser than the cast steel ball.  Steel grains are close together in forged steel, and there is no porosity in forged steel.  Even in high pressure ball valve (Class 900 and greater), the liquid medium could not penetrate into the forged steel ball.

Solid cast steel ball is an economical option.  Cast steel ball may contain some extent of porosity, and is unsignificantly less dense than forged steel ball.  In high pressure ball valve (Class 900 and greater), the liquid medium may penetrate into the tiny porosities of the cast steel ball.  In the fully-close position, for high pressure ball valves, there may be chance of micro leakage due to these tiny porosities of the cast steel ball.

Hollow welded steel ball is the sinful option.  These are used in Grade C ball valves, and sometimes employed in Grade B ball valves.  Welded steel ball is made of curved steel plates which are welded together.  Hence, the welded steel ball is hollow in side.  Easy way to differentiate the welded steel ball from the solid steel ball is the light weight of the welded steel ball.  Welded steel ball is not good because the liquid medium could enter into the hollow portion of the welded steel ball.  This would cause minor leakage of the ball valve in the fully-close position.

Before machining and finishing, we could easily identify the solid forged steel ball, solid cast steel ball and hollow welded steel ball.  However, after machining and finishing, all these 3 types of ball look visually similar.

Quality of the ball is also affected by the machining of the ball.  The best machining method is the CNC spherical grinder.  Second best option is CNC lathe fitted with rotating table, which would give a 5-axis machining capability.  CNC machining would enable the accuracy and precision of every single ball.  CNC spherical grinder is better than CNC lathe because the grinding will produce better smoothness and better roundness.  Grade A balls are always machined using CNC spherical grinders or CNC lathe with rotating table. 
Grade C ball are machined using manual lathe machine, which could not guarantee the consistency and precision; hence, slight dimensional variation among the balls; so some balls will be good, some balls may cause leakage.

Finishing of the ball should be mirror finish.  All Grade A balls have this mirror-like finish, which is easily achieved using CNC spherical grinder. 
On the opposite end, Grade C balls will be hand lapped, using lapping compound, after the manual machining is completed.  Manual machining also produce uneven roundness.  If the person doing the hand lapping is unskilled, the uneven roundness will be continued.  Grade C balls, being unevenly round and not mirror finished, will have tendency toward minor leakage.

With these explanations, I hope buyers could understand the importance of quality of Balls in the Ball Valves.  Quality of Ball affects significantly the price of the Ball Valve.  Quality of the Ball also plays a major role to determine the quality, reliability and durability of the Ball Valve.

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Wafer Check Valves

Wafer check valve is one category of check valve which has a more compact design, a shorter face-to-face dimension.

There are wafer swing check valves and wafer lift check valves.  Wafer swing check valves are more commonly used.

Advantages of wafer swing check valve as compared to regular swing valve:
1)  Wafer swing check valve has a shorter face-to-face dimension.
2)  Wafer swing check valve is lighter in weight than the regular swing check valve.
3)  Wafer swing check valve consume less space and less weight in a skid or oil and gas platform.

Wafer swing check valve could be dual-disc or single-disc.  Variation of the single-disc is the tilted single-disc.

Disadvantages of wafer swing check valve as compared to regular swing valve?
1)  Wafer swing check valves is generally more expensive than regular swing check valve on per kg basis.
2)  There are less valve factories manufacturing wafer swing check valves.

Wafer swing check valve could be dual-disc or single-disc.  Variation of the single-disc is the tilted single-disc.


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PMI on Duplex Stainless Steel and Stainless Steel

Positive Material Identification (PMI) is essential for the various types of stainless steels and corrosion-protection steel alloys.
Hence, PMI is essential for:
Stainless Steel 316, 304, 410, etc;
Duplex Stainless Steel (22% Cr);
Super Duplex Stainless Steel (25% Cr);
Hastelloy;
Inconel;
Monel.

For Duplex Stainless Steel and Stainless Steel valves, PMI is conducted by using PMI XRF portable test gun, pointed at the external surface of completed valves.  Parts of valves to be PMI tested are:
a)  Body,
b)  Bonnet;
c)  Stem (for all valves having externally-exposed stems).

For Duplex Stainless Steel and Stainless Steel, which are the more common materials used for oil and gas industry, the main material composition to be PMI tested are Chromium (Cr), Nickel (Ni) and Molybdenum (Mo).

Composition to be tested are as follows:

Material type	Steel Grade	Cr	Ni	Mo
Stainless Steel Casting	ASTM A351 Gr CF8M	18.0% - 21.0%	9.0% - 12.0%	2.0% - 3.0%
Duplex Stainless Steel Casting	ASTM A890 Gr 4A	21.0% - 23.5%	4.5% - 6.5%	2.5% - 3.5%
Stainless Steel Forging	ASTM A182 Gr F316L	16.0% - 18.0%	10.0% - 15.0%	2.0% - 3.0%
Duplex Stainless Steel Forging	ASTM A182  Gr F51	21.0% - 23.0%	4.5% - 6.5%	2.5% - 3.5%

The above are the most common types of stainless steel and duplex stainless used in valves for petrochemical, oil and gas industry.

For me, as a Quality Control Consultant for the past 2 decades, PMI (positive material identification) is the most important Quality Control practice for ensuring correct valve material, hence, the strength and properties of the specific types of steel.

 

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Forged Steel Ball Valves

Forged Floating Ball Valves are used mainly in Oil, Gas Transmission and Distribution Pipeline, Petroleum ,Chemistry, Chemical Fiber, Metallurgy, Paper Pulp etc. The forging material can ensure sufficient rigidity and strength under maximum rated operation pressure without inherent flaw of cast. The Forged Steel Body assures uniform fine grain structure and toughness free from inevitable casting defects such as porosity, abscess, crackle, gas hole. Enough wall thickness of separate Body and Adapters and high strength tie bolts are convenient for valve maintenance and sufficient to bear the stress of pipe.

Standards:

Design and manufacture -  API 6D / BS 5351

Pressure-temperature rating - ASME B16.34

Face to face dimensions - ASME B16.10

Flange type and dimensions – ASME B16.5

Butt-welded end – ASME B16.25

Inspection and test – API 598, ASME B16.34

Size range – NPS ½”  up to  NPS 8”

Pressure rating – 150 lb  to 300 lb

Fire Safe.  Forged Steel Floating Ball Valves fire safe is designed in compliance with API 607-4^th, API 6FA and BS 6755 Part 2. Each possible leakage parts between body and ball, middle flange, body and stem is designed as metal-to-metal contact, when non-metal resilient seats are damaged in a fire or unusual temperature increasing, the upstream medium pressure push the ball into the downstream metal seat lip to cut off the line fluid and prevent the internal leakage due to a secondary metal-to-metal seals.

Blow-out Proof Stem Design.  The stem is designed with integral T-type shoulder to provide blow-out proof effectively. The lower end of stem is terraced and installed from the lower internal part of stem. It is internally inserted as the back seat function to assure stem sealing safety at all pressures.

Locking Devices (on request). To prevent wrong operations of valve switch and improper actions by unpredictable, vibration of the line, the valve is equipped with locking hole at the full open and full close position of the valve, and the valve can be locked with a pad lock. Especially this locking device is uniquely advantageous when the valve is installed outdoors or on the production line of flammable petroleum or chemicals.

Handle Indicating Open/Closing Status of Valve.  Flat square structure is adopted for the head of valve stem which enables the correct connection with the handle and ensures the handle to be in the same direction with flow hole of the ball. When the handle is horizontal with pipeline of the valve, the valve is in the state of opening, when the handle is vertical with pipeline of valve, valve is in the status of closing.

Positive Material Identification - PMI

PMI is abbreviation for Positive Material Identification.

PMI is actively applied in the oil and gas industry.
Purpose of PMI includes:
1)  Check the correctness of material used for making a certain equipment.
2)  Check the content of alloying elements for a specific type of steel.
3)  Check the type of steel used, e.g. Stainless Steel 316, Stainless Steel 304, Stainless Steel 410, Duplex Stainless Steel 22% Cr, Super Duplex Stainless Steel 25% Cr.

How to do PMI?

PMI can be done using XRF or OES methods.

XRF is X-Ray Fluorescence.  XRF can be done using a portable analyzer or a desktop analyzer.  Desktop XRF analyzer is  suiable for test samples and small-sized products, tested in a lab or office environment.  Portable XRF analyzer is suitable for products as well as test samples, tested anywhere.  That's the beauty of portable XRF analyzer; it can be easily carried around for testing to be done anywhere, i.e. at site, at plant, at platform, at vendor's warehouse, at vendor's factory.

OES is Optical Emissions Spectroscopy.  OES is often used in test labs.  OES have an advantage over XRF, because OES can detect and measure Carbon (C) and Nitrogen (N).  Disadvantage is OES will create a "burn mark" on product tested, so it is  not truly non-destructive.  

ExxonMobil does not permit PMI using OES for testing the real products.

PMI for Valves

PMI is often used for checking the valve materials used, especially for the body and bonnet.  PMI is often used as a Quality Control practice if the body/bonnet material is made of stainless steel, duplex stainless steel, or super duplex stainless steel.