Lincoln Excalibur 8018-B2 MR is a premium low-hydrogen E8018-B2 welding rod engineered for welding 1.25 Cr – 0.5 Mo (P11/P12) chrome-moly steel in high-temperature power generation, petrochemical, and refinery piping applications. With H4R hydrogen designation and the Lincoln Excalibur moisture-resistant coating, Excalibur 8018-B2 MR provides code-compliant, low-hydrogen weld metal on Cr-Mo piping systems that must operate reliably at elevated temperatures from 850 to 1100 °F. It is the E8018-B2 welding rod specified by power plant and refinery welding engineers who need consistent chrome-moly weld metal with verifiable hydrogen control.
Excalibur 8018-B2 MR is Lincoln Electric's E8018-B2 low-hydrogen SMAW electrode with moisture-resistant (MR) flux coating. The AWS classification E8018-B2 decodes as: "E" = electrode; "80" = 80,000 psi minimum tensile; "1" = all-position; "8" = low-hydrogen iron-powder covering, DCEP; "B2" = 1.25 % Cr, 0.5 % Mo alloy deposit chemistry. The 1.25 Cr – 0.5 Mo alloy composition matches the P11 (ASME B31.3 Group 1.13) and P12 (ASME B31.3 Group 1.14) chrome-moly pipe specifications widely used in boiler feed water systems, hydrogen service piping, and refinery process lines operating between 850 and 1100 °F. Chromium improves oxidation resistance and creep strength at elevated temperature; molybdenum increases creep rupture strength and contributes to solid-solution strengthening at temperature. Post-weld heat treatment (PWHT) is mandatory for E8018-B2 welds on P11 pipe per ASME B31.1 and ASME B31.3 — PWHT relieves residual stresses and tempers the as-welded martensite in the weld metal and HAZ, restoring ductility and toughness. The MR designation means the flux coating is formulated with moisture-resistant binders that resist atmospheric moisture pickup more aggressively than standard low-hydrogen coatings — providing extended exposure time outside the oven before re-drying is required.
| Property | Specification |
|---|---|
| AWS Classification | E8018-B2 |
| AWS Standard | AWS A5.5/A5.5M |
| H-Designation | H4R (≤ 4 mL/100g diffusible H2) |
| Tensile Strength (min., PWHT) | 80,000 psi (551 MPa) |
| Yield Strength (min., PWHT) | 67,000 psi (462 MPa) |
| Elongation (min., PWHT) | 19% |
| Chromium Content | 1.00–1.50% |
| Molybdenum Content | 0.40–0.65% |
| Flux Type | Low-hydrogen iron-powder, MR |
| Current | DCEP |
| Positions | All |
| Diameters | 3/32, 1/8, 5/32, 3/16 in |
| PWHT Required | Yes — per applicable code (ASME B31.1, B31.3) |
- ASME P11 chrome-moly piping (1.25Cr-0.5Mo) — boiler headers, steam superheater piping, boiler feed systems, and turbine steam piping in power generation plants.
- ASME P12 piping (1Cr-0.5Mo per some B31 classifications) — compatible in many refinery applications per WPS procedure qualification.
- Refinery process piping in hydrogen service — operating at elevated temperatures and partial hydrogen pressures where Nelson curve compliance (API 941) requires 1.25 Cr – 0.5 Mo steel.
- High-temperature petrochemical heat exchangers — shell and tube exchangers in crude oil, heavy vacuum gas oil, and reformate service.
- Fossil fuel power plant boiler and pressure part fabrication — ASME Section I and B31.1 Code application for steam service to 1100 °F.
- Repair welding on in-service P11 piping — on-stream repair and weld repair under applicable fitness-for-service standards.
| Diameter | Amperage (DCEP) | Position |
|---|---|---|
| 3/32 in | 60–85 A | Root passes, thin pipe |
| 1/8 in | 80–115 A | General fill/cap passes |
| 5/32 in | 110–155 A | Fill passes, horizontal |
| 3/16 in | 145–195 A | Heavy fill passes |
Preheat: Preheat is mandatory for P11 Cr-Mo pipe per ASME B31.1/B31.3. Minimum preheat 300–400 °F for wall thickness > 0.5 in; check the applicable code and WPS for the exact preheat, interpass, and PWHT requirements for your specific pipe size and wall thickness.
PWHT: 1350–1400 °F (732–760 °C) for 1 hour per inch of wall thickness (1 hour minimum) per ASME B31.1 for P11. PWHT must be performed before hydrostatic testing. Cooling rate controls apply — consult the applicable code for controlled cooling requirements to avoid reheat cracking in heavy-section welds.
Hydrogen management: Maintain electrodes in a 250–300 °F holding oven. MR coating provides enhanced resistance but does not eliminate the oven storage requirement for long-duration production work. AWS D1.1 / ASME Section IX exposure limits apply.
- Sealed container: Store in sealed Lincoln container at room temperature. MR packaging provides extended shelf resistance to moisture.
- Holding oven (mandatory once opened): 250–300 °F once the container is opened. MR coating extends exposure time before redrying is needed — consult Lincoln's published MR electrode guide for specific exposure time tables.
- Redrying if needed: 700–800 °F for 1–2 hours if moisture is suspected.
- Contamination risk: Cr-Mo weld metal is particularly sensitive to hydrogen cracking due to higher hardenability. Strictly maintain preheat throughout the weld and eliminate moisture sources near the joint.
- ASTM A335 Grade P11 (1.25Cr-0.5Mo) pipe
- ASTM A387 Grade 11 Cr-Mo alloy pressure vessel plate
- ASTM A182 Grade F11 forgings
- ASTM A234 Grade WP11 pipe fittings
Joint types: groove welds on pipe and plate, fillet welds on attachment and support welds, and repair welds on in-service P11 components. All joints require prequalified or procedure-qualified WPS per ASME Section IX or the applicable power/process piping code.
Q: What does P11 pipe mean and why does it require special electrodes?
P11 refers to the ASME material group designation for 1.25 Cr – 0.5 Mo low-alloy chrome-moly steel used in elevated-temperature service (up to 1100 °F). The chromium and molybdenum additions provide oxidation resistance and creep strength at temperature that plain carbon steel lacks. These same alloying elements increase hardenability — the tendency to form hard, brittle martensite in the weld HAZ upon rapid cooling. Special low-hydrogen electrodes (E8018-B2) and mandatory preheat/PWHT protocols are required to prevent hydrogen cracking in the weld and HAZ.
Q: Why is PWHT mandatory for E8018-B2 welds on P11 pipe?
PWHT at 1350–1400 °F tempers the martensite in the as-welded HAZ, restoring ductility and toughness. Without PWHT, the hardened HAZ is brittle and susceptible to stress-corrosion cracking in hydrogen service and thermal-fatigue cracking during plant startup/shutdown cycles. ASME B31.1 and B31.3 both mandate PWHT for P11 above certain wall thicknesses.
Q: What is the difference between E8018-B2 and E9018-B3?
E9018-B3 is used for 2.25 Cr – 1 Mo steel (P22 pipe), which requires higher alloy content, higher preheat, and higher PWHT temperature than P11. E8018-B2 is specifically matched to P11 chemistry. Using E9018-B3 on P11 is generally overalloyed and does not violate codes, but E8018-B2 is the specified and qualified filler for most P11 procedures.
Q: What preheat do I need for 1.25 Cr – 0.5 Mo pipe welding?
ASME B31.1 requires 300 °F minimum preheat for P11 material in most thickness ranges. Specific requirements vary by wall thickness and carbon equivalent — always verify against the qualified WPS and applicable code section for the exact preheat, interpass maximum temperature (typically 600 °F maximum), and PWHT requirements for the job.
Q: What is the MR (moisture-resistant) designation on Excalibur 8018-B2 MR?
Lincoln's MR designation indicates the electrode flux has been formulated with moisture-resistant binders that reduce the rate of moisture pickup from the atmosphere compared to standard low-hydrogen coatings. This provides extended holding time outside the oven before redrying is required — practical for field welding where oven access is intermittent. It does not eliminate the oven requirement; it extends the permitted exposure window.
Q: Is E8018-B2 approved for ASME Section IX?
Yes. E8018-B2 is an F4 group filler metal under ASME Section IX QW-432 and qualifies for procedure tests on P5A/P5B chrome-moly base metals including P11 and P12.
Q: Can I use E8018-B2 without PWHT in an emergency repair?
Emergency weld repairs on P11 without PWHT are governed by fitness-for-service standards (API 579, ASME PCC-2) and require engineering authorization. Butter-bead or temper-bead welding techniques may be used to achieve in-place tempering without furnace PWHT — but these procedures require specific qualification and authorization. Never skip PWHT on production P11 pipe welds without explicit code or engineering authorization.
Chrome-moly (Cr-Mo) alloy steels are the workhorses of high-temperature power generation systems. The 1.25 Cr – 0.5 Mo composition (ASTM A335 Grade P11, ASTM A387 Grade 11) balances elevated-temperature strength, oxidation resistance, and weldability at a cost point that makes it the dominant specification for steam-temperature service below approximately 1050–1100 °F. Above 1100 °F, 2.25 Cr – 1 Mo (P22) or 9 Cr – 1 Mo (P91) steel is required. The E8018-B2 electrode chemistry mirrors P11 base metal composition in the weld deposit (1.0–1.5% Cr, 0.4–0.65% Mo), ensuring that the welded joint's creep-rupture properties match the parent metal over the component's design life. Lincoln Excalibur 8018-B2 MR is manufactured with premium-grade iron powder and controlled moisture-resistant binder chemistry that maintains the H4R classification (≤ 4 mL/100g diffusible hydrogen) across field temperature and humidity variations. For power plant pre-heat and PWHT compliance, Lincoln's published Excalibur 8018-B2 MR data sheet provides the specific preheat table (temperature vs. wall thickness), interpass maximum, PWHT temperature range, and cooling rate guidance required by ASME B31.1 Section 131.7 for P11 welds. Consult this data sheet and the applicable piping code for every P11 weld procedure to ensure full code compliance.