December 2021, Vol. 248, No. 12
Tech Notes
Proper Cleaning and Storage of Pipeline Pigs
Special to P&GJ
Proper storage and maintenance are important to ensure the optimal performance and condition of urethane pigs.
Apache pigs will perform as designed for pipeline cleaning, batching and displacement. However, urethane components are subject to deterioration under certain conditions – namely, heat, humidity and ultraviolet (UV) light.
To keep pigs in top shape, here are some guidelines that should be followed for proper storage and cleaning of pipeline pigs:
Heat and humidity will accelerate the deterioration of urethane pigs. To maximize shelf life, maintain a temperature around 80.6 degrees F (27 degrees C) and relative humidity less than 60%.
Because heat will affect the urethane, keep urethane pigs out of direct sunlight. Should the urethane components be exposed to extreme cold, warm the components to between 50 and 80.6 degrees F (10 and 27 degrees C) before use, since cold will cause the urethane to become brittle.
To prevent deformations of their shape, stack pig parts – this is especially important for pig cups. Use a “first in, first out” usage system to maintain shelf inventory.
Assembled Pigs
The ideal storage for pigs is on a stand, with a stand supporting the pig weight. To store brush and blade pigs, stand them on end. Otherwise, storing pigs with blades, springs or urethane cups on their sides will cause deformations of the cups and blades.
Removeable plug components need to be stored properly as well. Urethane pig cups can be stacked if the weight is not enough to distort the lowers cups. Urethane discs can be stacked as well. Any urethane parts that have been stored for six months or more should be examined for physical properties before being used.
Components that lose their physical properties will soften, darken in color and begin to flake or crumble. Should this occur, these parts need to be discarded.
You should also check for hardness by using a sharp tool. When pressed into the urethane, the amount of penetration should be minimal.
Use a durometer gauge for a more precise measure of non-metallic hardness. A cup or disc component with a hardness outside of manufacturing specs should be discarded.
When in doubt, contact the manufacturer for more information on the condition of the pig and pig-related products.
Cleaning
A pig needs to be cleaned as soon as possible after being removed from the pipeline. If the pig is heavily packed with paraffin, most of it can be removed by scraping immediately after the pig is removed from the trap.
Submerge the scraper in water heated to 158 degrees F (70 degrees C) for no more than an hour before scraping. Once the bulk of the paraffin has been removed, clean the remainder with a high-pressure water jet. A high-pressure jet can also be used to clean liquid residue from the pig.
Steam cleaning is acceptable for cleaning metal body parts and spring assemblies – but ONLY these parts! The maximum water temperature should be 185 degrees F (85 degrees C) for a maximum of 30 minutes. Any hotter or longer could cause damage to exposed urethane.
Solvents such as diesel fuel or kerosene also can be used to clean pigs. Urethane components can be immersed in or wiped with either one.
Proper storing and cleaning of pipeline pig inventory will save both time and money. It will also ensure the maximum effectiveness of your pigging product and project.
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