PTQ Q3 2026 Issue

Typical P&ID consideration The following aspects should be considered in piping and instrumentation diagrams (P&ID) development for salt dryers: • Provide a throttling valve at the dryer inlet for controlled filling. During filling, the flow should be limited to a maxi - mum of one-third of the normal feed flow rate to avoid dis - turbing the salt bed. Because the line size may be large, the valve capacity should be selected to give stable control at the target filling flow. This can be achieved by specifying a globe valve with reduced trim or characterised cage, or by providing a small-bore filling bypass fitted with a throttling valve or a restriction orifice. 𝐶𝑣 for glove valve should be verified, and the selected valve should be capable of main - taining this flow with a practical valve opening range. In normal operation, the inlet valve remains fully open, and throttling is used only during filling. • A flow meter is typically located downstream of the salt dryer, and this can be utilised to monitor flow during filling. If unavailable, install a flowmeter at the dryer inlet with suf - ficient straight run for orifice accuracy. • Include a bypass line around the dryer to enable continued operation during salt loading, maintenance, or shutdown/ start-up. • Brine may be routed directly to the oily water separator (OWS) or to a decant system if oil carryover is excessive. When routed to OWS, it is necessary to dilute or flush the line from time to time by adding water. In some refineries, brine is piped to the effluent treatment plant (ETP) using high-density polyethylene (HDPE) lines or routed to the desalter outlet line (caution: brine must never be routed to the slop system, as water drained from slop tanks is sent to the sour water stripping (SWS) unit, which has strict limita - tions on maximum allowable chloride content). • The brine drain line should be a minimum of 2 inches in diameter, preferably 3 inches or larger, to minimise plug - ging risk. Install an isolation valve at the vessel outlet and provide a hot water connection downstream for clearing blockages. • Connect a nitrogen line to maintain an inert atmosphere after salt loading and during draining, ensuring a slight pos - itive pressure. • Do not provide a steam-out connection, as steam may damage internal lining or protective coatings. • The vent line, ideally 4 inches in diameter and serving also as a salt gauge nozzle, should have a blind downstream of its isolation valve. Tap an overflow line upstream of the isolation valve and route it to grade OWS. Both vent and overflow lines must be blinded when not in use to prevent ULSD discharge to the atmosphere. • A bypass should not be installed across the pressure relief valve for venting, as this could allow backflow of toxic gases from the flare header. Since the dryer operates with stabilised ULSD (high flash point), it is safe to vent to the atmosphere, and a direct flare connection is not required for venting. • The brine maximum level must be maintained at least 250 mm below the inlet distributor. To ensure this, an inter - face-level indicator, a local-level gauge, and a high-level

alarm should be provided for reliable monitoring and oper- ational safety. Standpipes for interface instruments should preferably be at least 4 inches in diameter and sloped toward the vessel to minimise plugging and maintain con- tinuous circulation. Where feasible, direct mounting of the guided wave radar on the vessel is preferred • Heat tracing is recommended for level gauges, brine draw lines, the boot, and the bottom head of the dryer to main - tain the brine above the maximum operating temperature, thereby reducing the risk of salt precipitation and line plug - ging. The heat tracing cut-off temperature should be set at least 10 °C above the maximum operating temperature to compensate for ambient heat loss. • A differential pressure (DP) indicator is required across the salt bed. The transmitter should be installed at the top of the dryer, above the outlet line, with impulse lines routed accordingly to nullify the effect of the static leg inside the dryer. Note: Pressure drop typically increases as the salt bed depletes due to pore plugging. • A temperature indicator should be provided at the dryer inlet. • Include sampling points at the inlet, outlet, and brine drain of each dryer for performance monitoring. Operational practices Salt loading The following practices are recommended to ensure safe and effective salt loading in the dryer: • Inspect the inlet distributor and support grid, and verify ceramic rope caulking before commencing salt loading. • Perform leak testing of the bottom manway located below the salt bed. Any leakage through this manway after loading would necessitate the complete unloading of the salt and ceramic balls. • Personnel must not stand directly on the ceramic balls or salt bed. If access is required, a sufficiently wide wooden plank must be used to distribute weight safely. • Remove the brine drain isolation valve at the bottom of the vessel prior to ceramic ball loading. This creates an open path for any balls that may pass through the support grid or gaps between the grid and vessel wall; such gaps may result from damaged or improperly sealed ceramic rope. If ceramic balls are observed exiting, the support grid and sealing arrangements must be inspected and repaired before proceeding with salt loading. It is important to tem - porarily cover the open brine outlet line to prevent ingress of foreign material during loading. • Begin by manually bucket-loading the ceramic balls through the top manway to form the initial support layer. The first 100 mm of salt should also be loaded manually to avoid particle damage from free fall. After leveling the ceramic ball layer, confirm that no balls pass through the support grid. • Use a sock-loading arrangement for subsequent salt charging. The vertical gap between the sock outlet and the salt bed surface must not exceed 50-60 cm. Switch to shorter socks as the salt level rises. • For the upper sections where sock loading becomes impractical, use inclined loading pipes to guide the salt gently.

PTQ Q3 2026