Dover Midland A-720 Series Installation, Operation & Maintenance Manual Download Page 1

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Installation, Operation & Maintenance Manual

Part No.: A-720/A-721/A-721-B/A-724, Rev. 1.8

Issue Date: Jan 3, 2022

Supersedes: A-720/A-721/A-721-B/A-724, Rev. 1.7

Top-Transfer 2

Angle Valve

A-720, A-721 and A-724 Series

Installation, Operation

& Maintenance Manual

www.midland.com

Summary of Contents for Midland A-720 Series

Page 1: ...nce Manual Part No A 720 A 721 A 721 B A 724 Rev 1 8 Issue Date Jan 3 2022 Supersedes A 720 A 721 A 721 B A 724 Rev 1 7 Top Transfer 2 Angle Valve A 720 A 721 and A 724 Series Installation Operation Maintenance Manual www midland com ...

Page 2: ...and Parts Listings 4 SECTION 3 VALVE INSTALLATION 8 3 1 Installation and Required Tools 8 SECTION 4 OPERATING PROCEDURE 10 4 1 Opening the Valve 10 SECTION 5 VALVE QUALIFICATION 11 SECTION 6 VALVE DISASSEMBLY 15 SECTION 7 VALVE REASSEMBLY AND TESTING PROCEDURES 19 7 1 Cleaning 19 7 2 Reassembly Procedure 19 7 3 Testing Procedure 25 7 4 Post Test Procedures 25 SECTION 8 MAINTENANCE 26 8 1 Prior to ...

Page 3: ...nstructions carefully before proceeding Operation of the valve must conform to all applicable specifications from TC AAR DOT CFR Parts 173 31 174 67 etc and other governmental bodies along with the operating instructions of your company 1 2 SAFETY WARNINGS AND PRECAUTIONS Please carefully read each of the following warnings and cautions prior to performing any work WARNING Toxic Hazard Always use ...

Page 4: ... STEEL 720 8 CS STEEL 720 8 N60 NITRONIC 60 9A 1 PACKING WASHER TOP 720 93 SS STAINLESS 720 93 SS STAINLESS 720 93 SS STAINLES 9B 1 SPACER 720 95 SS STAINLESS 720 95 SS STAINLESS 720 95 SS STAINLESS 10 1 WIPER 713 33 PK PEEK 713 33 PK PEEK 713 33 PK PEEK 11 4 PACKING 720 11 TF TEFLON 720 11 TF TEFLON 720 11 TF TEFLON 12 1 STEM SEAL 720 12 BN BUNA N 720 12 BN BUNA N 720 12 BN BUNA N 13 1 O RING OUT...

Page 5: ...AL 720 12 BN BUNA N 13 1 O RING OUTLET 721 13 GY GYLON 3510 14A 1 HANDWHEEL NUT 10 15 SS STAINLESS STEEL 14B 1 WASHER 308 12 CS STEEL 15A 4 BOLT 724 15 SS STAINLESS STEEL 15B 4 LOCKWASHER 724 152 SS STAINLESS STEEL 16 1 OUTLET PLUG CHAIN 720 16 CS STEEL PLATED 18A 1 STEM RETAINER 720 18 SS STAINLESS STEEL 18B 2 NUT 720 181 SS STAINLESS STEEL 19 1 PIN 720 19 SS STAINLESS STEEL 20 1 RETAINER NUT 720...

Page 6: ...Installation Operation Maintenance Manual 6 Top Transfer 2 Angle Valves A 720 A 721 A 721 B and A 724 Series Figure 2 1 A 720 A 721 A 724 Valve Dimensions Component Identifications ...

Page 7: ...7 Top Transfer 2 Angle Valves A 720 A 721 A 721 B and A 724 Series Figure 2 2 A 721 B Valve Dimensions Component Identifications ...

Page 8: ...s of the groove to verify that there are no dents or burrs Since the valve fits tightly in the groove any peening of the groove edges may make it difficult to properly fit the valve s tongue into the groove 3 1 5 Up to this point the new valve should have been kept in its original shipping container and a special plastic protector should have been positioned over the tongue on the bottom of the va...

Page 9: ...tening will damage the valve s Teflon seat 3 1 13 Inspect the valve for leaks according to your company s procedures for this testing The primary areas to check are in the side port area the packing gland area the flange connection between the cover plate and the valve and seat In order to check the seat for leaks on an installed valve on the tank car pressure may be applied to the outlet flange w...

Page 10: ...k car supervisor The tank may be pressurized contain solidified product or the valve may be jammed 4 1 2 Examine the pipe plug Be sure its threads are clean free from corrosion not worn or crossed Also examine the threads on the side port to see that they are in good operating condition 4 1 3 This valve has an adjustable packing gland Routine maintenance consists of periodic inspection and adjustm...

Page 11: ...EL This part is designed to fail when the stem is over torqued If a spoke is cracked or broken off the handwheel must be replaced 5 1 2 STEM Roll the stem on a flat and true surface It will be apparent if the stem is bowed If you attempt to straighten it do not grip or deflect it on the ground surface in the packing seal area nor in the acme thread where deformation of the metal would make it diff...

Page 12: ... depth of 1 16 inch or if it has embedded debris discard it Replace it with a new seat seal from the factory This part is custom made for use on Midland valves only and must be purchased from Midland 5 1 5 OUTLET FLANGE The surfaces where the O ring fits and the flat gasket surfaces must be free of nicks scratches and pits Similarly the 2 or 3 NPT must be in good condition It can be cleaned with t...

Page 13: ...f nicks scratches and pits The internal wiper is clean without nicks and other defects This part is custom made for use on Midland valves only and must be purchased from Midland 5 1 8 The remainder of the parts are O rings packing gaskets bolts several types of nuts lock washers pins etc These are inexpensive parts and to ensure that the right sizes hardness strengths materials and correctly dimen...

Page 14: ...l component metal surfaces of the valves after cleaning inspection and specialized testing performed by agencies other than the repair facility are the responsibility of the repair facility 5 1 9 4 Where numerical tolerances cannot be provided the disposition of the internal integrity and surface quality of parts is under the jurisdiction of the repair facility and dependent on its experience and ...

Page 15: ...re that the stem is neither bent nor binding in the threaded part of the body item 4 Bent stems must be straightened to proceed with the disassembly 6 1 2 Place the valve in a vise gripping it on the flat faces of the 6 square flange with the stem horizontal and the side port on the top 6 1 3 Remove the pipe plug item 16 Body Figure 6 1 Turn handwheel Figure 6 2 Pipe plug removed Handwheel ...

Page 16: ... washers items 15A and 15B respectively 6 1 5 Carefully remove side outlet flange item 7 It may be necessary to insert two 2 screwdrivers 180 degrees apart between the flange and the valve body to pry it out Care to be taken so not to damage the mating surfaces between the body and flange Figure 6 4 Remove outlet flange Figure 6 3 Remove flange bolts and washers ...

Page 17: ...wn on the handwheel to keep the gasket retainer from rotating out of position 6 1 7 Take a 7 16 socket wrench and unscrew the nuts Using a block of steel that spans both sides of the U bolt about 1 wide tap the block to loosen the U bolt and push it out about 1 4 Open the handwheel again and rotate the gasket retainer 180 then tighten down on the handwheel to put tension on the gasket retainer The...

Page 18: ...asket retainer Then use a tool to pull the U bolt out 6 1 10 The packing gland item 11 can now be pulled out of the body with the standard packing tools 6 1 11 Loosen or remove the packing locknut see step number 6 1 9 Turn the handwheel to lower or raise the stem as far as it will go Then take off the handwheel nut washer and handwheel Gripping on the flats of the stem square with an open end wre...

Page 19: ... wiper item 10 in the body item 4 with the wiper side up see Figure 7 1 7 2 2 Put the spring item 5 in the body see Figure 7 1 7 2 3 Install the upper curved packing washer item 9 in the body with the convex side up see Figure 7 1 7 2 4 The 2 valve use four x4 Teflon V rings item 11 in the body see Figure 7 1 7 2 5 Insert the stem seal item 12 with Teflon insert in the packing screw item 8 see Fig...

Page 20: ...top of the packing screw see Figure 7 2 7 2 9 Put on the handwheel item 1 and then the handwheel lock washer item 14 By hand screw the handwheel nut item 14 onto the stem as far as it will go see Figure 7 2 7 2 10 Turn the handwheel counter clockwise to move the stem up into the neck of the body It should move easily After several turns stop when the stem thread come into contact with the lower pa...

Page 21: ...ace seat seal item 10 in the gasket retainer item 2 place the seal washer on top of the seat seal as shown 7 2 11 3 Make sure seal washer is flat with the seat seal 7 2 11 4 Hand tighten the retainer nut item 20 and use calibrated torque wrench to tighten the retainer nut item 20 to 35 ft lbs 7 2 11 5 If the slot matches with the pin hole no need to tighten further If not tighten to next slot CAUT...

Page 22: ...Figure 7 5 Reassembly steps 7 2 11 6 through 7 2 11 7 Figure 7 6 Reassembly step 7 2 11 8 7 2 11 6 Place the pin item 19 into the hole as shown tap the pin into place 7 2 11 7 Place the retainer assembly into the fixture as shown 7 2 11 8 Use the handle of press fixture to insert the pin as shown in Figure 7 6 ...

Page 23: ... side port see Figure 7 7 7 2 14 Insert the stem retainer U bolt through the holes in the retainer and the groove of the stem to couple these parts Lightly tap in the U bolt so the threaded ends go as far through the gasket retainer holes as the base of the U bolt will permit see Figure 7 7 7 2 15 Open the valve about turn and rotate the gasket retainer 180 and reclose the valve Install the two re...

Page 24: ...17 Screw in the flange bolts with lock washers item 15 hand tighten and then wrench tighten the bolts using the alternate tightening pattern Do not exceed 45 ft lb Check for uniform spacing between the two flange faces Correct by loosening and retightening see Figure 7 8 7 2 18 Tighten packing screw item 8 Tighten to 65 ft lb for all valve models 7 2 19 Tighten packing locknut item 21 to 65 ft lb ...

Page 25: ...cord those values on a test report if applicable and on a tag affixed to the valve which also indicates the organization performing the test 7 3 5 There are several acceptable methods of checking for a seat leak but one simple way is to put pieces of wide masking tape across the side port Put a small hole in the center of the tape and cover the hole with a little soap suds solution Any leak will t...

Page 26: ... angle valve not to be a part of the Resealing Rebuild or Remanufacturing of the valve or fitting The face plate or outlet flange may be changed as a regular part of maintenance without the removal from the railcar All proper assembly techniques torque specification as well as leak testing are required to be performed to ensure the proper performance requirements are met CAUTION The repair procedu...

Page 27: ...7733 Gross Point Road Skokie IL 60077 Tel 847 677 0333 Fax 847 677 0138 www midlandmfg com ...

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