February 15, 2023 | 3 minute read
John Crane strengthened the relationship with a customer and provided an efficient, timely and cost-effective solution through the successful installation and commissioning of the Type 2800 Pump Gas Seal.Background
An India-based petrochemical plant customer requested John Crane to investigate potential mechanical seal options and provide a solution to an ongoing clog issue on their pumps and failed seals.Customer Challenge
During the project execution stage, the liquid injection pumps installed in the customer’s Linear Low-Density Polyethylene/High-Density Polyethylene (LLDPE/HDPE) swing unit came fitted with a competitor’s mechanical seals (HRSG2 with API Plan 32, 74). These were identified as bad actors, with a mean time between failure (MTBF) of less than 12 months, and in some instances just three months. This resulted in frequent unit downtime and caused production losses ranging from 24-48 hours.
Observations on the pump and failed seals revealed blockages of Plan 32 and 74 ports, powder deposition inside the seal cavity and around the throat bush, resulting in the formation of a polymer ring behind the inboard seal to be the main reasons for the failures.John Crane Solution
John Crane reviewed the pump application and operating parameters, as well as the conditions leading to the failures and the nature of failures of the installed competitor mechanical seal.
John Crane’s Type 2800 Pump Gas Seal with special features (i.e., bi-directional design, expeller design sleeve) and with Circulation Plans 32 and 74 were offered. The bi-directional seal mitigated the risk of the pump reverse rotating and the expeller design prevented ingress of polymer powder/slurry into the seal cavity. The face-to-face configuration resulted in Plan 32 Outer Diameter (OD) pressurization preventing clogging of the springs and facilitating the seal to operate in a clean nitrogen envelope.Results
John Crane’s installed solution has completed one year of satisfactory service and is still in service. There are A & B pumps and standard operating procedure is to change over from A to B every three months. For a particular application, the plant may have two or three pumps. Under normal operations of the plant, one pump will be in operation with the others on stand-by. Pump A, installed with John Crane sealing solution, is in continuous operation while pump B is in continuous stand-by.