diff --git a/Detectors/FIT/FT0/simulation/src/Detector.cxx b/Detectors/FIT/FT0/simulation/src/Detector.cxx
index fb756adba7df5..342da8df726a0 100644
--- a/Detectors/FIT/FT0/simulation/src/Detector.cxx
+++ b/Detectors/FIT/FT0/simulation/src/Detector.cxx
@@ -294,6 +294,13 @@ void Detector::SetCablesA(TGeoVolume* stl)
 
   TVirtualMC::GetMC()->Gsvolu("0CAA", "BOX", getMediumID(kAir), pcableplane, 3); // container for cables
   TGeoVolume* cableplane = gGeoManager->GetVolume("0CAA");
+  // A hole for the beam pipe. The cable container spans the whole A-side face and
+  // would otherwise fill the pipe bore, which belongs to the beam-pipe vacuum. The
+  // pipe outer radius here is 2.5 cm and the nearest cable sits at r = 5.68 cm.
+  const float kBeamPipeHoleRadius = 3.;
+  new TGeoBBox("0CAAbox", pcableplane[0], pcableplane[1], pcableplane[2]);
+  new TGeoTube("0CAAhole", 0., kBeamPipeHoleRadius, pcableplane[2] + 0.1);
+  cableplane->SetShape(new TGeoCompositeShape("0CAAshape", "0CAAbox-0CAAhole"));
   //  float zcableplane = -mStartA[2] + 2 * mInStart[2] + pcableplane[2];
   int na = 0;
   double xcell[24], ycell[24];
diff --git a/Detectors/HMPID/simulation/include/HMPIDSimulation/Detector.h b/Detectors/HMPID/simulation/include/HMPIDSimulation/Detector.h
index 9e9a78914049e..c37452c167430 100644
--- a/Detectors/HMPID/simulation/include/HMPIDSimulation/Detector.h
+++ b/Detectors/HMPID/simulation/include/HMPIDSimulation/Detector.h
@@ -55,7 +55,7 @@ class Detector : public o2::base::DetImpl<Detector>
   void EndOfEvent() override { Reset(); }
 
   // for the geometry sub-parts
-  TGeoVolume* createAbsorber(float tickness);
+  TGeoVolume* createAbsorber(int chamber, float tickness);
   TGeoVolume* createChamber(int number);
   TGeoVolume* CreateCradle();
   TGeoVolume* CradleBaseVolume(TGeoMedium* med, double l[7], const char* name);
diff --git a/Detectors/HMPID/simulation/src/Detector.cxx b/Detectors/HMPID/simulation/src/Detector.cxx
index 83bab71e7177d..6205d6781c446 100644
--- a/Detectors/HMPID/simulation/src/Detector.cxx
+++ b/Detectors/HMPID/simulation/src/Detector.cxx
@@ -538,12 +538,15 @@ void Detector::createMaterials()
   Medium(kAr, "Ar", matId, unsens, itgfld, maxfld, tmaxfd, stemax, deemax, epsil, stmin);
 }
 //**************************************************************************************************
-TGeoVolume* Detector::createAbsorber(float tickness)
+TGeoVolume* Detector::createAbsorber(int chamber, float tickness)
 {
   double cm = 1, mm = 0.1 * cm, um = 0.001 * mm; // default is cm
   auto& matmgr = o2::base::MaterialManager::Instance();
   TGeoMedium* al = matmgr.getTGeoMedium("HMP_Al");
-  TGeoVolume* abs = gGeoManager->MakeBox("Habs", al, tickness * mm / 2, 1300.00 * mm / 2, 1300 * mm / 2);
+  // one volume per chamber: the two plates differ in thickness, so a shared name
+  // would leave two different volumes answering to "Habs" and two placements whose
+  // node paths are both /cave_1/barrel_1/Habs_0
+  TGeoVolume* abs = gGeoManager->MakeBox(Form("Habs%d", chamber), al, tickness * mm / 2, 1300.00 * mm / 2, 1300 * mm / 2);
   return abs;
 }
 //**************************************************************************************************
@@ -1260,8 +1263,8 @@ void Detector::ConstructGeometry()
 
   TGeoVolume* hmpcradle = CreateCradle();
 
-  TGeoVolume* hmpidabs_cham2 = createAbsorber(40.0);
-  TGeoVolume* hmpidabs_cham4 = createAbsorber(80.0);
+  TGeoVolume* hmpidabs_cham2 = createAbsorber(2, 40.0);
+  TGeoVolume* hmpidabs_cham4 = createAbsorber(4, 80.0);
 
   double theta = 33.5;
 
@@ -1270,14 +1273,14 @@ void Detector::ConstructGeometry()
   pMatrixAbs2->SetTranslation(trans2);
   pMatrixAbs2->RotateZ(theta);
 
-  gGeoManager->GetVolume("barrel")->AddNode(hmpidabs_cham2, 0, pMatrixAbs2);
+  gGeoManager->GetVolume("barrel")->AddNode(hmpidabs_cham2, 2, pMatrixAbs2);
 
   TGeoHMatrix* pMatrixAbs4 = new TGeoHMatrix;
   const double trans4[] = {435., 0., 155.};
   pMatrixAbs4->SetTranslation(trans4);
   pMatrixAbs4->RotateZ(theta);
 
-  gGeoManager->GetVolume("barrel")->AddNode(hmpidabs_cham4, 0, pMatrixAbs4);
+  gGeoManager->GetVolume("barrel")->AddNode(hmpidabs_cham4, 4, pMatrixAbs4);
 
   for (Int_t iCh = 0; iCh <= 6; iCh++) { // place 7 chambers
     TGeoVolume* hmpid = createChamber(iCh);
diff --git a/Detectors/MUON/MCH/Geometry/Creator/src/Station1Geometry.cxx b/Detectors/MUON/MCH/Geometry/Creator/src/Station1Geometry.cxx
index 1820f22afe25d..f1289f72b3700 100644
--- a/Detectors/MUON/MCH/Geometry/Creator/src/Station1Geometry.cxx
+++ b/Detectors/MUON/MCH/Geometry/Creator/src/Station1Geometry.cxx
@@ -892,18 +892,18 @@ void createFrame(int chamber)
   y = 2 * (kHyInHFrame + kHyH1mm) + kIAF + kHyV1mm;
   Mlayer->AddNode(gGeoManager->GetVolume("SQ01"), 1, new TGeoTranslation(x, y, z));
 
-  // TopFrameAnode - place 2 layers of TopFrameAnode cuboids
+  // TopFrameAnode - place 2 layers of TopFrameAnode cuboids. The Inox layer is
+  // stacked on top of the Epoxy one, as for SQ17to23/SQ18to24 below, so its centre
+  // sits at the Epoxy half-thickness and not at its own.
   x = kHxTFA;
   y = 2 * (kHyInHFrame + kHyH1mm + kHyInVFrame) + kIAF + kHyTFA;
-  z = kHzOuterFrameInox;
-  Mlayer->AddNode(gGeoManager->GetVolume("SQ02"), 1, new TGeoTranslation(x, y, -z));
-  Mlayer->AddNode(gGeoManager->GetVolume("SQ03"), 1, new TGeoTranslation(x, y, z));
+  Mlayer->AddNode(gGeoManager->GetVolume("SQ02"), 1, new TGeoTranslation(x, y, -kHzOuterFrameInox));
+  Mlayer->AddNode(gGeoManager->GetVolume("SQ03"), 1, new TGeoTranslation(x, y, kHzOuterFrameEpoxy));
 
   // TopFrameAnode - place 2 layers of 2 trapezoids (SQ04 - SQ07)
   x += kHxTFA + 2 * kH1FAA;
-  z = kHzOuterFrameInox;
-  Mlayer->AddNode(gGeoManager->GetVolume("SQ04toSQ06"), 1, new TGeoTranslation(x, y, -z));
-  Mlayer->AddNode(gGeoManager->GetVolume("SQ05toSQ07"), 1, new TGeoTranslation(x, y, z));
+  Mlayer->AddNode(gGeoManager->GetVolume("SQ04toSQ06"), 1, new TGeoTranslation(x, y, -kHzOuterFrameInox));
+  Mlayer->AddNode(gGeoManager->GetVolume("SQ05toSQ07"), 1, new TGeoTranslation(x, y, kHzOuterFrameEpoxy));
 
   // TopAnode1 - place 2 layers
   x = 6.8 + kDeltaQuadLHC;
diff --git a/Detectors/Passive/src/Pipe.cxx b/Detectors/Passive/src/Pipe.cxx
index 60c2256ba04bd..defd0dd0fd8ea 100644
--- a/Detectors/Passive/src/Pipe.cxx
+++ b/Detectors/Passive/src/Pipe.cxx
@@ -741,21 +741,22 @@ void Pipe::ConstructGeometry()
   zPos = aluSideA->GetZ(13) + flangeASteelRing->GetDz();
   barrel->AddNode(voflangeASteelRing, 1, new TGeoTranslation(0., 30., zPos));
 
-  // The vacuum inside aluSideA and flangeASteelRing
-  TGeoPcon* aluSideAVac = new TGeoPcon(0., 360., 8);
+  // The vacuum inside the aluminium section. aluSideA is a hollow Pcon, so it does
+  // not contain its own bore and the vacuum is a daughter of the barrel. The bore
+  // is kept at the third section's inner radius all the way to kZ36: the wider
+  // flange bore beyond it is occupied by the RB24 vacuum modules.
+  TGeoPcon* aluSideAVac = new TGeoPcon(0., 360., 6);
   aluSideAVac->DefineSection(0, aluSideA->GetZ(0), 0., aluSideA->GetRmin(0));
   aluSideAVac->DefineSection(1, aluSideA->GetZ(1), 0., aluSideA->GetRmin(1));
   aluSideAVac->DefineSection(2, aluSideA->GetZ(2), 0., aluSideA->GetRmin(2));
   aluSideAVac->DefineSection(3, aluSideA->GetZ(7), 0., aluSideA->GetRmin(7));
   aluSideAVac->DefineSection(4, aluSideA->GetZ(8), 0., aluSideA->GetRmin(8));
-  aluSideAVac->DefineSection(5, aluSideA->GetZ(11), 0., aluSideA->GetRmin(11));
-  aluSideAVac->DefineSection(6, aluSideA->GetZ(12), 0., aluSideA->GetRmin(12));
-  aluSideAVac->DefineSection(7, aluSideA->GetZ(13), 0., aluSideA->GetRmin(13));
+  aluSideAVac->DefineSection(5, aluSideA->GetZ(13), 0., aluSideA->GetRmin(9));
 
   TGeoVolume* voaluSideAVac = new TGeoVolume("aluSideAVac", aluSideAVac, kMedVac);
   voaluSideAVac->SetLineColor(kGreen);
   voaluSideAVac->SetVisibility(1);
-  voaluSideA->AddNode(voaluSideAVac, 1, gGeoIdentity);
+  barrel->AddNode(voaluSideAVac, 1, new TGeoTranslation(0., 30., 0.));
 
   // The support ring on A Side
   TGeoTube* sideASuppRing = new TGeoTube(kAluminum2ndSectionOuterRadius, kSupportRingRmax, kSupportRingLength / 2.);