Ductile Iron Drain Elbow — Low-Point Drain-Off Fitting

By Nico Yin · Qingdao Zhaoyuqi Machinery Co., Ltd.

Overview

A drain elbow is a pipe fitting designed for the lowest points of a piping system, where the line must be emptied, flushed, or drained of condensate. In its most common form it is a 90° elbow whose body incorporates a drain outlet — a tapped boss or a female-threaded drain port on the outer radius of the bend — so a plug, gauge, or drain valve can be mounted directly on the fitting. Cast in ductile iron to ASTM A536-84(2019), it withstands the impact loads and handling of outdoor water-works service far better than gray iron equivalents.

Typical installations include irrigation mains and hydrant laterals that must be drained before freezing, fire protection system low-point drain legs, underground network flush points, and pump suction pits where sediment accumulates at the bend. Because the drain port sits on the outside of the curve — the natural settling zone — debris collects where it can actually be removed, rather than blocking the downstream line. Standard threaded sizes run 1/2" to 6", with flanged bodies available for larger water-main work.

Specifications

Customization & Sampling

Drain elbows are a customization-friendly product: drain port size and position, boss height for insulation clearance, and the addition of a second port are all pattern-level decisions we can adjust from your drawing. The sampling sequence is drawing review → pattern/core adaptation → first article → gauge and pressure check → approval → production, with first samples typically ready in 3–5 weeks. If you send a used fitting from an existing network, we can reverse-engineer it and restore worn threads to standard gauge.

Quality Inspection & Packaging

Chemistry is verified per melt by optical emission spectrometry to the A536 band, and mechanical coupons confirm tensile and elongation values. Inspection points specific to this fitting are the drain port thread gauge, boss wall thickness after machining, waterway continuity, and — for flanged versions — face flatness and bolt-hole circle. Pneumatic leak testing of the drain port plug interface is available on request. Parts are coated after QC and packed in export plywood cases or on pallets, drain ports face-protected. The factory operates a quality management system conforming to ISO 9001:2015 requirements.

FAQ

Q1: Where exactly should a drain elbow be installed?

At the true low point of the line, on the outer radius of the bend where water and sediment collect. Installing it anywhere else leaves residual water that can freeze or corrode — the classic failure cause in irrigation and fire mains in cold climates.

Q2: Is the drain port supplied with a plug?

We can supply the elbow with a square-head ductile iron plug fitted, or the port only. Many customers pair it with our square head plugs; specify plug material and coating in your inquiry.

Q3: Which coating survives a buried drain chamber?

Hot-dip galvanizing plus a bituminous overcoat, or a fusion-bonded epoxy, are the usual choices for permanently damp chambers. For above-ground dry locations, standard bituminous paint is sufficient and more economical.

Related Products

• Square Head Plugs

• Elbow (Standard 90°)

• 90° Base Elbow

• Coupling

• Check Valve

Get a Quote

WhatsApp usWhatsApp us at +86 185 6156 7088 the main size, drain port size, coating, and quantity for a same-day-style response — our export team typically returns a formal quotation within one working day. If the drain elbow is part of a larger fitting package for a water or irrigation project, send the full bill of materials and we will quote the package with consolidated packing and shipping.

Need a formal quotation? Send your Ductile Iron Drain Elbow drawing, quantity and target price through our RFQ form — it goes straight to the foundry inbox, and we reply with a priced offer, material certificate draft and production lead time within one business day.