1、AEROSPACERECOMMENDED PRACTICE ARP4266 Issued 1997-11 Reaffirmed 2014-10 Hole Contour, Fluid Passage, Tube Fitting RATIONALE ARP4266 has been reaffirmed to comply with the SAE five-year review policy. _ SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the
2、state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefrom, is the sole responsibility of the user.” SAE reviews each technical report at least every five
3、 years at which time it may be revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions. Copyright 2014 SAE International All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted, in any form or by any mea
4、ns, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: +1 724-776-4970 (outside USA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org S
5、AE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/ARP4266 1. SCOPE:This document is intended to provide recommended contours and limits of size of the surfaces of the internal fluid passages of tube fittings for the portions that a
6、re not already defined by the fitting end design standard drawings.1.1 Purpose:The internal passages of fittings are defined by the dimensions of the fitting end design standards, a through hole diameter that may be smaller than that on the fitting ends, an allowable mismatch of holes on the same ax
7、is, a minimum wall thickness of the center body section of shape fitting and a requirement for a minimum ball to pass through shape fittings. This document provides manufacturing recommendations to reduce abrupt changes in contours and thus minimize pressure drop, reduce the number of edges produced
8、 to minimize burrs and provide sufficient minimum size of fluid passages while maintaining a minimum wall thickness of the center body section, which is defined herein. The historical background of the need for this document is given in 4.1.2. REFERENCES:The following publications form a part of thi
9、s document to the extent specified herein. The latest issue of SAE publications shall apply. The applicable issue of other publications shall be the issue in effect on the date of the purchase order. In the event of conflict between the text of this document and references cited herein, the text of
10、this document takes precedence. Nothing in this document, however, supersedes applicable laws and regulations unless a specific exemption has been obtained.2.1 ASME Publications:Available from ASME Order Department, 22 Law Drive, Box 2300, Fairfield, NJ 07007-2300.ASME B46.1 Surface Texture (Surface
11、 Roughness, Waviness, and Lay)3. REQUIREMENTS:3.1 Minimum Wall Thickness:3.1.1 For straight fittings, such as unions, adapters, reducers, caps and plugs, the internal hole diameter and length should be specified with the hole ending in a conical end of 110 minimum included angle. A full spherical ra
12、dius may be optional. If necessary a flat bottom may be specified.3.1.2 For shape fittings, such as elbows, tees and crosses, a section thickness shall be specified as “Minimum wall thickness of center body section” as shown in Figure 1.FIGURE 1 - Optional Callouts for Minimum Wall Thickness3.1.3 Th
13、e “center body section” is defined as that portion of the shape fitting that is not dimensioned by the individual fitting end design standards except the internal passage hole may be the minimum hole from the design standard. See examples in Figure 2.SAE INTERNATIONAL ARP4266 Page 2 of 10_ FIGURE 2
14、- Examples of Center Body Sections of Shape Fittings3.2 Contours and Limits of Size of Internal Fluid Passages of Shape Fittings:3.2.1 The suggested sequence of production of the internal passage holes with their contours and limits of size for the four basic shapes, 90 elbow, 45 elbow, tee and cros
15、s, are shown in Figures 3 through 14.FIGURE 3 - 90 Elbow, Non-ReducerSAE INTERNATIONAL ARP4266 Page 3 of 10_ FIGURE 4 - 90 Elbow, ReducerFIGURE 5 - 45 Elbow, Non-ReducerSAE INTERNATIONAL ARP4266 Page 4 of 10_ FIGURE 6 - 45 Elbow, ReducerFIGURE 7 - Tee, Non-Reducer or Reducer on SideSAE INTERNATIONAL
16、 ARP4266 Page 5 of 10_ FIGURE 8 - Tee, Reducer on RunFIGURE 9 - Tee, Reducers on Run and SideSAE INTERNATIONAL ARP4266 Page 6 of 10_ FIGURE 10 - Tee, Reducer on Both RunsFIGURE 11 - Cross, Non-ReducerSAE INTERNATIONAL ARP4266 Page 7 of 10_ FIGURE 12 - Cross, Reducer on Run OnlyFIGURE 13 - Cross, Red
17、ucer on Run and SideSAE INTERNATIONAL ARP4266 Page 8 of 10_ FIGURE 14 - Cross, Reducer on Three Sides3.2.2 The following notes also apply to each of the Figures 3 through 14:a. The spherical radius at the end of the hole shall be required on the largest diameter hole of elbows and may be machined at
18、 the end of all holes.b. The mismatch at mating holes on the same axis may be .015 maximum.c. The minimum wall thickness of the fitting center body section shall be met.d. The surface finish of spherical or conical ends of holes shall be 250 in Ra per ASME B46.1.4. NOTES:4.1 Background:In 1951 the m
19、ilitary standards for flareless fittings were published with specified drill depths for the fluid passage hole in each leg. In the late 1950s, fitting manufacturers issued company standards for flareless reducer fittings with formulas for the drill depth of fluid passage holes noted on each standard
20、. These were often in conflict with airframe company and other manufacturers standards. In 1962, 37 flared reducer fitting standards were published by SAE Committee G-3B with formulas for the drill depths given on each standard. The parameters for these formulas were not well defined and calculation
21、s by various users often resulted in different dimensions.SAE INTERNATIONAL ARP4266 Page 9 of 10_ 4.1 (Continued):To avoid repeated calculations, flareless reducer fitting standards were published in 1966 by G-3B with tabulated tables of drill depths for each leg and for each reducer size. In 1983,
22、calculated drill depth tables were added to the flared reducer fittings by G-3B. Continued dimensional problems with some of the calculated drill depths were to be addressed with a 1984 G-3B project to prepare a proposed ARP4266 to specifically define how to calculate drill depths. In 1991, after lo
23、ng efforts by the project sponsor, it was determined that it was not practical to specify formulas to calculate drill depths. It was agreed by G-3B to specify minimum wall thickness values for the center body section of shape fittings as necessary to meet the performance requirements specified for t
24、he fittings. At that time a separate G-3B project resulted in a recommendation for the fluid passage hole as follows:“The contour at the bottom of the hole is optional; it may be curved or conical.”In 1994, G-3B agreed that to reduce pressure drop, a full radius round bottom in the hole intersection
25、 of elbows is desirable. This document is meant to address the above recommendations.4.2 Dimensions:All dimensions are in inches.4.3 Key Words:Minimum wall, drill depth, center body, fittingPREPARED BY SAE SUBCOMMITTEE G-3B, AEROSPACE FITTINGS OF COMMITTEE G-3, AEROSPACE COUPLINGS, FITTINGS, HOSE AND TUBING ASSEMBLIESSAE INTERNATIONAL ARP4266 Page 10 of 10_
