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CTF: Clean-Up of Cryogenic Piping

A. Purpose

This procedure describes how to purge the helium piping to remove unwanted contamination before cool down.

B. Initial Condition

CTF is warmed up, the recovery system is running, and the recovery system suction/discharge is cross-connected to the main compressor suction/discharge respectively

C. This document contains highlighted flow paths EDM screens to purge the follow systems: 1. CTF Valve Box 2. CTF CB1 3. CTF CB2 4. CTF CB4 5. Junction Box 6. Compressor Systems For more accurate information, see the P&I’s

D. Procedure 1. Make a log entry.

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2. Connect auxiliary helium supply to Valve box port C a. Systematically flow through each path or through all paths in parallel insuring to set up

enough DP to ensure that there is a DP across each path. i. Ensure that CPI2440 does not go above the relief set point

a. 5.5 atm is a good target to purge all the Valve box paths at the same time ii. Ensure that the recovery suction is not overwhelmed iii. Ensure that all downstream pressures are within limits

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iv. Open EV2456 & EV27910 (VTA Bayonet Can) and flow from Valve Box port C

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v. Flow through cryo module ambient vaporizer

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vi. Flow Back to CB4

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3. Purge CB1 / VTA Shield Circuit

i. CB1; Control flow from the compressor discharge to the recovery system using MV2400, CEV2402, & CEV2401 and by-passing the expansion engine with a copper tubing connected from “x” to “H”

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4. Reverse flow the High pressure side of CB2

5. CB4

a. HP supply; Controlling flow with either EV2082 or EV2084 b. The low side was purged with the valve box but will also be purged when the cryo

module is purged.

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6. Purge the expansion engines and then install expander u-tubes a. Run engines with GN2 connected to each of the expander’s inlet bayonet for a

maximum of 15minutes (Ensuring the outlet temperature does not get to low) b. Run engine with helium connected to each of the expander’s inlet bayonet for a

maximum of 15minutes i. Ensuring the outlet temperature does not get to low ii. Connecting to the inlet bayonet with the auxiliary helium supply

c. Install U-Tubes i. Expanders 2A and 2B u-tubes purge source

i. Auxiliary helium supply to the CB2 3 atm supply bayonet ii. Ensure that the outlet valve (EV2440) is open

ii. Expander 1

a. Source gas connected to by-pass ¼” tubing

7. There is no plan to setup purges on the compressors. They should be isolated from any

contamination coming from the cold boxes and only started after the rest of the system is clean.