What are Appendix-2 flanges? Firstly, the name stems from the fact that they are found in Appendix-2 of ASME VIII-1.
Secondly, they are custom flanges. This allows the designer the flexibility to manipulate the different flange variables, unlike flanges designed to ASME B16.5 and ASME B16.47, which fully describe materials, dimensions and pressure ratings for flanges.
Design Options:
- Style: Appendix-2 flanges can be designed in a number of configurations, such as slip-on, lap joint, and weld neck, even for very large flanges.
- Dimension: Aside from the flange configuration, some other variables that can be manipulated are the bolt circle diameter, number and size of bolts, hub thickness and length, flange thickness and outer diameter.
- Shape: Appendix-2 flanges can be circular or non-circular. However, there does not appear to be any provision for a non-circular bore in Appendix-2. Hence, only the flange’s outside edge can be of another shape.
- Split: Flanges designed to Appendix-2 can be split loose flanges, where the flange is split into two halves. Further, an Appendix-2 split flange can be designed as a pair of concentric split rings, where the splits are offset by 90°.
Limitations:
- Gasket: For an Appendix-2 flange, the gasket must be completely contained within the bolt circle diameter. This prevents the use of a full-face gasket on an Appendix-2 flange.
- Contact: There must be no metal-to-metal contact outside of the bolt-circle diameter in an Appendix-2 flange. If there is any metal-to-metal contact the flange will most likely fall under Appendix-Y.
- Loads: Appendix-2 calculations cover the hydrostatic end load, called the operating condition, and the gasket seating condition only. Thus it is designed for pressure loads only. The effect of external piping loads must be accounted for separately.
The name sounds rather silly, and it brings to mind something like a potato gun, but launching something much larger than a potato. This is, of course, not at all what a pig launcher is.
“Pigging” is the term used for the process of sending an object through a pipeline using pressure. This can be used to clean pipes, and also to inspect the pipeline for corrosion or leaks. A pig launcher will inject a pig, which is an object slightly larger than the pipe diameter and short enough to traverse any bends, into the pipeline and sent down the pipeline by means of the pressure in the product being carried down the pipeline.
Pigs can be used to separate different fluids in the pipeline, as well as fluids of different batches, but they are often used to clean the inside of the pipe. It is this property that makes pigging useful not just for pipelines but for smaller piping systems as well. Application of pigging can reduce the cost of cleaning pipelines and piping systems, and eliminate the need to use harsh solvents to clean the pipes when switching between different fluids being used in the same piping system.
There are not a lot of examples of Appendix-Y calculations available. What are Appendix-Y flanges? They are found in Appendix-Y of ASME VIII-1, hence the endearing title “Appendix-Y.”
- Appendix Y is a custom flange. Unlike ASME B16.5 and ASME B16.47, which fully describe materials, dimensions and pressure ratings for flanges, Appendix-Y allows the designer is able to manipulate various criteria.
- Appendix Y is used for a very specific type of flange joint. Each flange must be flat-faced, parallel to the mating flange, and there must be metal-to-metal contact outside of the bolt circle. This precludes full-faced gaskets and any flange design where the faces don’t make contact outside the bolt circle. However, it does allow for flanges with a metal spacer, where the spacer contacts both flange faces, which themselves don’t touch.
- This type of flange makes use of a self-energizing gasket that is roughly in line with the wall of the attached pipe or vessel. The gasket seating loads are neglected, and the hydrostatic end loads dominate the calculations.
- Typically, the flanges will be thinner than an Appendix-2 flange, but the bolting requirements can be surprisingly high.
- These flanges are often used in a low-pressure application. A similar flange-style is used by the drinking water industry, but they are not covered by ASME VIII-1.
CSA B51:
In Ontario, TSSA does not automatically accept all of CSA B51’s definitions and positions for boilers and pressure vessels. The jurisdiction has the final authority, and can choose to accept or deny any code, or portion of code, as they deem fit. Furthermore, TSSA can also apply their own interpretation to the codes that they allow. TSSA’s Code Adoption Document (BPV-08-01), published May 1, 2008, lists what sections of the CSA B51 code are adopted, and what changes are made to it.
ASME Boiler and Pressure Vessel Code:
ASME codes become mandatory 6 months after the Date of Issuance. This is written in the Foreword to each code. As per the ASME site, one can make use of these codes before they are in effect by stating the year the code is published in. However, it is typical for Canadian jurisdictions to require the edition + addenda to be fully specified on the drawing.
TSSA will accept codes as soon as they are published, even before they become mandatory, but does not mandate it prior to the end of the six-month period. As well, TSSA will accept an older code if the purchase order for the project is dated when the older version of the code was still valid. This is also stated in the Foreword to the ASME Codes, as seen below.
Excerpt from Foreword of ASME codes,
After Code revisions are approved by ASME, they may be used beginning with the date of issuance. Revisions, except for revisions to material specifications in Section II, Parts A and B, become mandatory six months after such date of issuance, except for boilers or pressure vessels contracted for prior to the end of the six-month period.
SAE J518 covers the specification of four-bolt split flanges that attach tubes, pipes, and hoses to applicable ends. These flanges are intended for use in hydraulic applications.
However, most jurisdictions will not register fittings for use in a hydraulic application. Can flanges conforming to the shape and materials of SAE J518 be CRN registered? If so, how does one go about registering such a flange?
If the flange is for use on a system with an expansible fluid the Jurisdictions will register it, provided that it conforms to an appropriate code. See ABSA’s Pressure Equipment Safety Regulation User Guide for definition of expansible.
a) If the material and shape of the design conforms to SAE J518, then the flange can be CRN registered under the SAE J518 code. This is acceptable through ASME B31.3-2008 326.1.1, and Table 326.1, which states that the SAE J518 code is used to fully define the dimensions and pressure rating of these flanges directly, with no alterations required.
b) If the material does not conform to the requirements of SAE J518, while the shape of the design does, then the flange may be registered using ASME VIII-1 Appendix Y. The Jurisdictions have accepted calculations assuming three bolts, equally spaced around the centre, that satisfy the code requirements as covering the four-bolt flanges described in SAE J518.
ACI Central has a guideline for using FEA in CRN submissions, and is available upon request. It can be found here (current as of 2010). It varies significantly from ABSA’s AB-520 guideline (click here). ACI Central’s guideline follows the requirements in ASME VIII-2 2007 ed Part 2, “Responsibilities and Duties”, for both the User’s Design Specification and the Manufacturer’s Design Report (Annex 2.B). These Code guidelines are reasonable when designing a pressure vessel, with ASME VIII-2 as the Code of Construction, using FEA only. However, conflicts arise when obtaining a CRN from ACI for a catalog of small fittings designed to ASME B31.3, when the only reason for using FEA is to bridge gaps in the standard Code configurations. In fact, it is impossible to comply with all the requirements of these guidelines for fittings, though it is still possible to obtain CRN approval.
For more information or help with CRN registration, contact Key Design Engineering
A) With Metal-to-Metal contact outside of the Bolt-Circle Diameter (BCD):
Must use Appendix-Y calculation in ASME VIII-1, or FEA (Finite Element Analysis) if it doesn’t conform to the standard configuration. Not all pressure vessel software packages will do Appendix-Y, but with a bit of effort it can be programmed into a spreadsheet or other mathematical programs. Key Design Engineering has the capability of calculating Appendix-Y flanges.
B) Without Metal-to-Metal contact outside of the BCD:
ASME VIII-1, 2-2(b) specifies how to calculate the bolt loads for “self-energizing” gaskets, such as o-rings. The seating requirement is negligible, and really the only load is the operating condition to support the hydrostatic end force H. Please see the Code for more details.
For more information, please contact Key Design Engineering
If you need a good starting point for components that already carry a CRN, or at least help to find manufacturers & suppliers who are familiar with obtaining CRNs, here is a list that provides a few to “set you rolling”.
Some Components with a CRN
If you need a CRN or ASME calcs for your pressure component, contact Key Design Engineering
Per ASME B16.9 Factory-Made Wrought Buttwelding Fittings, the components must be verified by either “mathematical analyses” or “successful proof test data”.
What is accepted by the Canadian Jurisdictions, for registration per B16.9?
-Proof tests are the usual way of successfully registering in Canada. Not only are the hand calculations quite extensive (if you can actually calculate them all), but some jurisdictions will refuse to consider them. It is noised about that FEA can potentially be used as well, though perhaps they would need to be registered under an umbrella code such as VIII-1 or B31.3, rather than as a B16.9 component.
But, how to deal with the daunting number of components and combination of sizes and pipe schedules for burst testing? Section 9.4 in B16.9 has different applicability rules that can be followed to cover different sizes, thickness ranges, and material grades. This will greatly reduce the number of individual tests that must be performed.
Contact Key Design Engineering for more assistance.
Recently I’ve come across companies who will readily supply a CRN number when requested (like for a fitting). However, when they are asked to produce the documentation, either:
- The CRN is expired by up to 4 years ago in the case that I’m thinking of right now, or
- Different parameters: in other cases it is for a different material than what is currently being purchased, or
- Different Jurisdiction: maybe even for a different province.
Do they not realize that they aren’t in compliance? Perhaps not, otherwise they wouldn’t be so quick to hand over their registration letter. In any case, it seems rather unfair that some companies can get away with doing this, while others have followed protocol and bear the full cost for maintaining the documentation. One way that a person can check CRNs is go to acicentral.com, under the “Silent Inspector”.
