multipass - nordcousers manual multipass 125 railroad ave beacon falls, ct 06403 phone: +1 (203)...

USERS MANUAL

MultiPass

125 Railroad Ave Beacon Falls, CT 06403

Phone: +1 (203) 438-9696

Document: 1102340

MultiPass USERS MANUAL

© 2 0 1 5 N o r d c o

07/16/2015 of 12 Revision A

Contents

1 Introduction ...................................................................................................................................................... 3

2 RFD Testing Details ........................................................................................................................................... 3

2.1 Couplant .................................................................................................................................................... 3

2.2 Chassis Alignment ...................................................................................................................................... 3

2.3 RSU Alignment ........................................................................................................................................... 3

2.4 Oscilloscope ............................................................................................................................................... 4

2.5 Switches ..................................................................................................................................................... 4

2.6 Gain ............................................................................................................................................................ 4

3 System Verification ........................................................................................................................................... 5

3.1 0° (Zero-Degree) Transducer Channel ....................................................................................................... 6

3.2 37.5° Transducer Channel ......................................................................................................................... 7

3.3 70° Transducer Channels ........................................................................................................................... 9

3.4 Side Looker Channels ............................................................................................................................... 11


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1 Introduction The Nordco Multi-Pass Rail Flaw Detection (RFD) instrument is very basic by its nature:

One (1) Rolling Search Unit (RSU) with 6 transducers o One (1) 0° o One (1) 37.5° o One (1) 70°-center o One (1) 70°-left o One (1) 70°-right o One (1) Side Looker-Fill Side

One (1) Oscilloscope to view 1 transducer channel at a time

One (1) Switching box to select the transducer channel displayed

One (1) Water storage and delivery tank

Mechanical Alignment Chassis

2 RFD Testing Details Ten (11) passes along a single piece of rail are required to complete a thorough RFD inspection.

0° (one single pass in either the forward or reverse direction)

37.5° (one pass forward & one pass in the reverse direction)

70°-center (one pass forward & one pass in the reverse direction)

70°-left (one pass forward & one pass in the reverse direction)

70°-right (one pass forward & one pass in the reverse direction)

Side Looker (one pass forward & one pass in the reverse direction)

2.1 Couplant Couplant between the RSU & Rail is absolutely necessary to allow sound to pass between the two. Note that any that foams will inhibit sound passage. Never add foaming agents or surfactants to the Couplant. Enough Couplant should be supplied between the RSU & Rail to ensure sound penetration.

2.2 Chassis Alignment The Chassis must be kept perpendicular to the rail at all times during testing. Any angle, or CANT, that is introduced between the Multi-Pass and the Rail introduces dead-zone areas or the rail that are not inspected. The Multi-Pass Operator must ensure proper orientation of the Chassis throughout testing.

2.3 RSU Alignment The RSU must be aligned to the rail for proper operation. The 0° transducer must be perpendicular to the base of the rail for this to be feasible. Loosen the bolts on the RSU yoke and turn the RSU cable connector with a wrench (never grab and turn the cable with your hand). Use the Oscilloscope on the 0° channel to “peak” the return signal from the base of the rail. Note that for optimal “peaking”, the 2nd back-wall echo should be maximized (this requires increasing the gain beyond normal testing levels to visualize the 2nd back-wall echo).


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2.4 Oscilloscope Ensure the Range on the Oscilloscope is great enough to visualize the inspection area in the rail. Note that the Oscilloscope “ZERO” & “DELAY” settings can impact the displayed signals (see the Sitescan User’s Guide for more information).

2.5 Switches Switches on the Switching Box determine what channel is displayed on the Oscilloscope. Only one Switch should be ON at a time. Switches are labeled according to the channel that will be displayed when the switch is turned ON:

“0°” – displays the 0° channel

“45°” – displays the 37.5° channel (“45°” is a widely used legacy term relating to earlier inspection techniques)

“SL” – displays the Side Looker transducer (Fill Side of the, inspecting the Plain Side)

“70° L” – displays the Left 70° transducer

“70° C” – displays the Center 70° transducer

“70° R” – displays the Right 70° transducer

2.6 Gain Ultrasonic Signal Gain settings on the Oscilloscope should be determined based on the 70’s transducers. Gain settings for the other channels (0°, 37.5°, & Side-Lookers) can be adjusted via the dials on the Switch Box. Turning a channel ON also imposes the dial adjustments to the channel Gain level.


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3 System Verification Periodically (at the beginning of a testing day, and throughout a testing day as environmental and rail conditions and characteristics vary), the system must be validated to ensure Oscilloscope (primarily Gain) settings for proper RFD. Known track structures allow for system verification.

0° – Rail Base echoes

37.5° – Bolt Hole indications (“walking” through the Scope display)

70° Channels – Joint or Rail End indications

Side Looker Channels – Switch Point indications Additional RFD skills and knowledge can be provided through a Training Program as supplied by Nordco. For further training, please contact Nordco.


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3.1 0° (Zero-Degree) Transducer Channel

0° (Zero-Degree) Transducer Channel

The 0° (Zero-Degree) Transducer Channel uses a longitudinal sound beam to inspect for horizontal defects in the head, web, and base (only in the area directly below the web) such as split heads and webs, and to detect cracked or elongated bolt holes. It also detects vertical split heads (lack of response from the base of the rail). This beam is directed normal to the rail running surface, penetrating through the web to the rail base. It will also detect any defect that masks the bottom of the rail echo such as a vertical split head or an internal defect at an angle that reflects the 0°. The 0° (zero degree) beam is also used to ensure the probe wheel is aligned over the web of the rail. One Inspection Pass per piece of rail is adequate.


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3.2 37.5° Transducer Channel

37.5° Transducer Channel

The 37.5° Transducer Channel uses a shear beam to primarily inspect for bolt-hole defects in the web of the rail. However, it will also detect discontinuities in the head and base (only in the area directly below the web) if that discontinuity is relatively perpendicular to the 37.5° beam, such as peculiarly aligned transverse defects missed by the seventy degree (70°) transducers.


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Two (2) Inspection Passes per piece of rail are required for RFD with the 37.5° channel – 1(one) in the forward direction (while facing the Multi-Pass in the forward direction) & 1 (one) in the reverse direction (while facing the Multi-Pass in the reverse direction). Note that the Multi-Pass chassis MUST change orientation for the second pass.


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3.3 70° Transducer Channels

70° Transducer Channels

The 70° Transducer Channels are used to inspect the head of the rail for defects in the Transverse plane of the rail such as TD's and defective welds. There are three 70° shear wave transducers built in to a single array; each beam inspects a different portion of the rail (center, left, & right). However, the Multi-Pass Oscilloscope can display a single channel at a time, therefore multiple passes are required for complete RFD.


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Six (6) Inspection Passes per piece of rail are required for RFD with the 70° channels – three (3) in the forward direction, one for each of the center, left, & right channels (while facing the Multi-Pass in the forward direction) & 3 (three) more passes in the reverse direction, again with the center, left, & right channels (while facing the Multi-Pass in the reverse direction). Note that the Multi-Pass chassis MUST change orientation for the second set of 3 (three) passes.


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3.4 Side Looker Channels

Side Looker Transducer Channels

The Side Looker Transducer Channel is a shear wave beam aimed through the head of the rail, and therefore is called "side looking". This channel i s used mainly to test for vertical split head defects especially those that are located away from the centerline (web area). The Side Looker Transducer is mounted on the Fill Side of the RSU but is aimed towards the opposite side of the rail.


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Two (2) Inspection Passes per piece of rail are required for RFD with the Side Looker channel – 1(one) in the forward direction (while facing the Multi-Pass in the forward direction) & 1 (one) in the reverse direction (while facing the Multi-Pass in the reverse direction). Note that the Multi-Pass chassis MUST change orientation for the second pass.

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