I learned how to hydrotest major chemical and crude pipelines in less than 3 months
I developed a process (the troubleshooting part is the most important) to run them successfully.
Establishing frameworks to apply to all jobs when I saw patterns of how they were ran, what went wrong, and how the issues were fixed.
In this post I'll explain from cradle to grave how I run successful hydrotests, and how you can use it to run your own.
With any project you need to prepare before you execute a plan. The most important part of the preparation phase is the site visits to determine:
- What staging area you are working with
- How to get water into the line
- Where to dispose of waste
- Hazards to equipment and people
- When to start work (school zones, chemical plants, etc)
You should be with people from site and the surrounding area to ask as many questions as you can. No question is a stupid question.
Have every contractor you know will be needed on the walk with you. Make a point to voice any concerns about the job.
Common equipment and personnel you'll need for hydrotesting
- frac tanks for water/fluid storage
- excavators and hydroexcavators for potential leaks
- flare for decommissioning and recommissioning
- water source (ponds, trucked in water, etc)
- temporary traps for tool runs
- mats for heavy equipment and trailers
- welders/fitters for modifying pipe
Additionally, you need to think ahead for the next test. What can you improve while the line is down that may help the next project? Where were the last project's equipment staged? Can we position things better for the people working?
Most of these pipelines are older than your parents, and were built without any intention to be tested at regular intervals. Bring them into the 21st century by looking at what a good hydrotest setup looks like and develop the project as close to that vision. You're company and the people on the next project will thank you.
Now that you have an idea of the place you're working with, identify the key players of the job. These groups are
- Product Coordinator
- Controls Coordinator
- Field Execution Team
It makes sense to have a daily/weekly email sent out depending on the length of the project. Talk with these teams to determine what are the key details they need to know at each stage.
- project schedule
- potential leak sites
- project budget
- equipment and movements affected
- Key tasks for each day/week
Keeping everyone in the loop can easily be done through message/visuals. Keep the calls to a minimum and you'll save time and headache on cost and schedule.
Actual execution is where the fun begins. Isolating the test line from other equipment and pipelines should follow a double block and bleed procedure. Having full seals on each or the ability to stop flow completely is crucial for preventing safety incidents
Depending on the product you have the option of flaring or suctioning and storing. Flaring requires permits that you fill out well in advance. You can calculate the amount to be flared by quick calculations in Excel or online
If evacuating the line you should use swabs and cleaning pigs in order to clean the line. This is especially important if a tool is to be run through the line. Most tools run in water have issues with data collection in a dirty line. Do the work on the front end to prevent additional runs and lost time on schedule. Additionally, perform the suction at the lowest point of the line. Let gravity help you get all the product out rather than spending time blowing the line down.
Optional Tool Runs
As part of integrity assessments, a tool run can be required. Tool runs during hydrotests are done because the line is usually hard to get down time or requires a specialty tool that can navigate the line. It's simpler to perform during the water fill because you aren't worried about delaying line drying.
To get a successful run, make sure the line is clean and you have an appropriate pump to push the tool at the right speed (1-3 mph is the range for most tools).
Water fill and testing
Whether you have run the tool or filling the line with water, the water fill begins by taking your water source (tank, pond, etc) and using the pump to fill the line and pressurize to a holding pressure. You want a full line pack that you can monitor for 24 hours (stablization period) before you begin the hydrotest.
After the 24 hour hold period, you can begin your test. Start by pressurizing the line in steps to ensure the test equipment is reading properly and you aren't seeing any leaks or small issues with the equipment on the line.
Know your test pressures per ASME B31.4 prior to testing. Use a upper and lower range to give yourself breathing room in case there are other issues with the test
Common issues when Hydrotesting
Pressure Loss from leaks/fluctuation from temperature swings
Pressure losses and fluctuations can be mitigated by using the right fittings and materials for the test. Tight but not too tight, closing valves, and using the proper bolts/gaskets go a long way to prevent a larger issue.
When planning a hydrotest, plan for a start during the early morning and begin at a lower range test pressure. You then have the ability to let the ambient heat provide some pressure from thermal expansion rather than going above test pressure and releasing water to compensate.
Find a good time period to do an 8 hour test. preferably the middle period of the day or night depending on the urgency. Gaining or losing sunlight mid test is what causes tests problems.
Stopping tests too early
You may not know when you started a test, but it's a good decision to continue a test if there is doubt on the 8 hour window being achieved. There's more than enough time, water, and people necessary to continue a test and have the records show good data.
Inaccurate recording of water added/released
When adding and releasing water you need to be meticulous in the amounts used. PHMSA requirements are killer when it comes to detail. Be on site to talk with those operating the pumps to determine the volumes that were injected or bled off.
I like to think of Decommissioning and Recommissioning as similar to jumping a car battery - to get back to normal operation you perform the same steps in reverse
- drain the water from the line
- push cleaning pigs with nitrogen in order to dry to the required dew point of the product
- bolt up connections used
- reintroduce the product until the vapor pressure is reached and liquid is able to fill the line
While every job is different each job follows a similar procedure. You can follow this framework to run efficient hydrotests and meet PHMSA requirements.
If you have questions or need help with running your own hydrotest, DM me on here and we can discuss strategies and action plans for your next hydro!